phosphocreatine and Disease-Models--Animal

Duchenne muscular dystrophy (DMD) is an X-linked muscle disorder characterized by progressive and irreversible loss of muscular function. As muscular disease progresses, the repair mechanisms cannot compensate for cellular damage, leading inevitably to necrosis and progressive replacement by fibrous and fatty tissue. Cardiomyopathy and respiratory failure are the main causes of death in DMD. In addition to the well-described muscle and heart disease, cognitive dysfunction affects around 30% of DMD boys. Myocardial fibrosis, assessed by late gadolinium enhancement (LGE), using cardiovascular magnetic resonance imaging (CMR), is an early marker of heart involvement in both DMD patients and female carriers. In parallel, brain MRI identifies smaller total brain volume, smaller grey matter volume, lower white matter fractional anisotropy and higher white matter radial diffusivity in DMD patients. The in vivo brain evaluation of mdx mice, a surrogate animal model of DMD, showed an increased inorganic phosphate (P(i))/phosphocreatine (PCr) and pH. In this paper, we propose a holistic approach using techniques of magnetic resonance imaging, spectroscopy and diffusion tensor imaging as a tool to create a "heart and brain imaging map" in DMD patients that could potentially facilitate the patients' risk stratification and also future research studies in the field.

Topics: Animals; Anisotropy; Brain; Cardiomyopathies; Cognitive Dysfunction; Diffusion Tensor Imaging; Disease Models, Animal; Fibrosis; Gray Matter; Heart; Heterozygote; Humans; Hydrogen-Ion Concentration; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Mice; Mice, Inbred mdx; Muscular Dystrophy, Duchenne; Myocardium; Organ Size; Phosphates; Phosphocreatine; White Matter

The effects of 20th-century stress on the cardiovascular system are reviewed and correlated with experimental animal models. A classic example of such stress is drawn from a study of the aerospace workers at Cape Kennedy who were shown to be exposed to excessive occupational stress. Surprisingly, the usual risk factors did not predict a greater risk, yet the population exhibited a higher incidence of sudden cardiac death and acute myocardial infarction. Acute myocardial necrosis was much more frequently demonstrated than was acute coronary obstruction of any type. Retrospective coroner's studies revealed two types of myocardial necrosis: 1) elongated, thinned or wavy fibers and 2) anomalous contraction bands. Correlation of these clinical observations with experimental data was duplicated in canine models of myocardial infarcion and/or catecholamine-induced necrosis. Catecholamines can lead to irreversible myocardial necrosis but the underlying mechanisms appear to be complex. Extrapolation of the results from the experimental and clinical studies suggests that environmental stress can lead to myocardial necrosis.

Topics: Adenosine Triphosphate; Animals; Catecholamines; Coronary Circulation; Coronary Disease; Death, Sudden; Disease Models, Animal; Environment; Fear; Heart Arrest; Humans; Isoproterenol; Myocardial Infarction; Necrosis; Phosphocreatine; Stress, Psychological; Time Factors

Topics: Adenosine Triphosphate; Animals; Cell Nucleus; Citrates; Coronary Disease; Disease Models, Animal; Dogs; Endoplasmic Reticulum; Glycogen; Heart Arrest; Hypothermia; Microscopy, Electron; Mitochondria, Muscle; Myocardium; Phosphates; Phosphocreatine; Potassium; Potassium Chloride; Procaine; Rats

Prostate cancer is the second most common cause of cancer mortality in men worldwide. Applying a novel genetically engineered mouse model (GEMM) of aggressive prostate cancer driven by deficiency of the tumor suppressors PTEN and Sprouty2 (SPRY2), we identified enhanced creatine metabolism as a central component of progressive disease. Creatine treatment was associated with enhanced cellular basal respiration in vitro and increased tumor cell proliferation in vivo. Stable isotope tracing revealed that intracellular levels of creatine in prostate cancer cells are predominantly dictated by exogenous availability rather than by de novo synthesis from arginine. Genetic silencing of creatine transporter SLC6A8 depleted intracellular creatine levels and reduced the colony-forming capacity of human prostate cancer cells. Accordingly, in vitro treatment of prostate cancer cells with cyclocreatine, a creatine analog, dramatically reduced intracellular levels of creatine and its derivatives phosphocreatine and creatinine and suppressed proliferation. Supplementation with cyclocreatine impaired cancer progression in the PTEN- and SPRY2-deficient prostate cancer GEMMs and in a xenograft liver metastasis model. Collectively, these results identify a metabolic vulnerability in prostate cancer and demonstrate a rational therapeutic strategy to exploit this vulnerability to impede tumor progression.. Enhanced creatine uptake drives prostate cancer progression and confers a metabolic vulnerability to treatment with the creatine analog cyclocreatine.

Topics: Animals; Creatine; Creatinine; Disease Models, Animal; Humans; Intracellular Signaling Peptides and Proteins; Male; Membrane Proteins; Mice; Phosphocreatine; Prostatic Neoplasms

To evaluate signal changes in the hippocampus of epileptic seizure rat models, based on quantified creatine chemical exchange saturation transfer (CrCEST) signals.. CEST data and. Measured CrCEST signals were exhibited significant differences between before and after KA injection in the ES group. At each time point, CrCEST signals showed significant correlations with PCr concentration (all |r| > 0.59; all P < 0.05); no significant correlations were found between CrCEST signals and tCr concentrations (all |r| < 0.22; all P > 0.05).. CrCEST can adequately detect changes in the concentration of Cr as a result of energy metabolism, and may serve as a potentially useful tool for diagnosis and assessment of prognosis in epilepsy.

Topics: Animals; Creatine; Disease Models, Animal; Image Processing, Computer-Assisted; Magnetic Resonance Spectroscopy; Male; Phosphocreatine; Rats, Wistar; Seizures

Evidences have suggested that the phosphoryl transfer network by the enzymatic activities of creatine kinase (CK), adenylate kinase (AK), pyruvate kinase (PK), and lactate dehydrogenase (LDH), shows new perspectives to understand some disturbances in the energy metabolism during bacterial infections. Thus, the aim of this study was to evaluate whether Staphylococcus aureus infection in mice could alter serum and cardiac activities of these enzymes and their association to disease pathophysiology. For that, we measured total leukocytes, lymphocytes and neutrophils (just 48 h of infection) that were lower in infected animals after 48 and 72 h in infected mice compared with negative control, while total protein and globulin plasma levels were higher after 72 h of infection. The serum CK activity was higher in infected animals 48 and 72 h post-infection compared to the control group, as well as observed for mitochondrial cardiac CK activity. The serum PK activity was higher in infected animals after 72 h of infection compared to the control group, and lower in the cardiac tissue. The cardiac AK activity was lower in infected animals 48 h and 72 h post-infection compared to the control group, while serum and cardiac LDH activities were higher. Based on these evidences, it is possible to conclude that the stimulation of CK activity exerts a key role as an attempt to maintain the bioenergetic homeostasis by the production of phosphocreatine to avoid a rapid fall on the concentrations of total adenosine triphosphate. In summary, the phosphoryl transfer network can be considered a pathway involved in the improvement on tissue and cellular energy homeostasis of S. aureus-infected mice.

Topics: Adenosine Triphosphate; Adenylate Kinase; Animals; Creatine Kinase; Creatine Kinase, Mitochondrial Form; Disease Models, Animal; Endocarditis; Energy Metabolism; Heart; Homeostasis; Leukocytes; Liver; Lymphocytes; Male; Mice; Mice, Inbred BALB C; Mitochondria, Heart; Neutrophils; Phosphocreatine; Pyruvate Kinase; Spleen; Staphylococcal Infections; Staphylococcus aureus

What is the central question of this study? The aim of this study was to evaluate the potential beneficial effects of endurance training during an ischaemia-reperfusion protocol in a mouse model of sickle cell disease (SCD). What is the main finding and its importance? Endurance training did not reverse the metabolic defects induced by a simulated vaso-occlusive crisis in SCD mice, with regard to intramuscular acidosis, mitochondrial dysfunction or anatomical properties. Our results suggest that endurance training would reduce the number of vaso-occlusive crises rather than the complications related to vaso-occlusive crises.. The aim of this study was to investigate whether endurance training could limit the abnormalities described in a mouse model of sickle cell disease (SCD) in response to an ischaemia-reperfusion (I/R) protocol. Ten sedentary (HbSS-SED) and nine endurance-trained (HbSS-END) SCD mice were submitted to a standardized protocol of I/R of the leg, during which ATP, phosphocreatine and inorganic phosphate concentrations and intramuscular pH were measured using magnetic resonance spectroscopy. Forty-eight hours later, skeletal muscles were harvested. Oxidative stress markers were then measured. Although the time course of protons accumulation was slightly different between trained and sedentary mice (P < 0.05), the extent of acidosis was similar at the end of the ischaemic period. The initial rate of phosphocreatine resynthesis measured at blood flow restoration, illustrating mitochondrial function, was not altered in trained mice compared with sedentary mice. Although several oxidative stress markers were not different between groups (P > 0.05), the I/R-related increase of uric acid concentration observed in sedentary SCD mice (P < 0.05) was not present in the trained group. The spleen weight, generally used as a marker of the severity of the disease, was not different between groups (P > 0.05). In conclusion, endurance training did not limit the metabolic consequences of an I/R protocol in skeletal muscle of SCD mice, suggesting that the reduction in the severity of the disease previously demonstrated in the basal state would be attributable to a reduction of the occurrence of vaso-occlusive crises rather than a decrease of the deleterious effects of vaso-occlusive crises.

Topics: Acidosis; Adenosine Triphosphate; Anemia, Sickle Cell; Animals; Biomarkers; Disease Models, Animal; Endurance Training; Ischemia; Mice; Muscle, Skeletal; Oxidative Stress; Phosphocreatine; Physical Conditioning, Animal

The present study was designed to further explore the role and the underlying molecular mechanism of phosphocreatine (PCr) for cardiac fibrosis

Topics: Animals; Apoptosis; Disease Models, Animal; Fibrosis; Gene Expression Regulation; Heart Diseases; Humans; Isoproterenol; JNK Mitogen-Activated Protein Kinases; Matrix Metalloproteinase 9; Myocytes, Cardiac; NF-kappa B; Phosphocreatine; Rats; Signal Transduction; Tissue Inhibitor of Metalloproteinase-1; Transforming Growth Factor beta1

Mitochondrial creatine kinase (MtCK) couples ATP production via oxidative phosphorylation to phosphocreatine in the cytosol, which acts as a mobile energy store available for regeneration of ATP at times of high demand. We hypothesized that elevating MtCK would be beneficial in ischaemia-reperfusion (I/R) injury.. Mice were created over-expressing the sarcomeric MtCK gene with αMHC promoter at the Rosa26 locus (MtCK-OE) and compared with wild-type (WT) littermates. MtCK activity was 27% higher than WT, with no change in other CK isoenzymes or creatine levels. Electron microscopy confirmed normal mitochondrial cell density and mitochondrial localization of transgenic protein. Respiration in isolated mitochondria was unaltered and metabolomic analysis by 1 H-NMR suggests that cellular metabolism was not grossly affected by transgene expression. There were no significant differences in cardiac structure or function under baseline conditions by cine-MRI or LV haemodynamics. In Langendorff-perfused hearts subjected to 20 min ischaemia and 30 min reperfusion, MtCK-OE exhibited less ischaemic contracture, and improved functional recovery (Rate pressure product 58% above WT; P < 0.001). These hearts had reduced myocardial infarct size, which was confirmed in vivo: 55 ± 4% in WT vs. 29 ± 4% in MtCK-OE; P < 0.0001). Isolated cardiomyocytes from MtCK-OE hearts exhibited delayed opening of the mitochondrial permeability transition pore (mPTP) compared to WT, which was confirmed by reduced mitochondrial swelling in response to calcium. There was no detectable change in the structural integrity of the mitochondrial membrane.. Modest elevation of MtCK activity in the heart does not adversely affect cellular metabolism, mitochondrial or in vivo cardiac function, but modifies mPTP opening to protect against I/R injury and improve functional recovery. Our findings support MtCK as a prime therapeutic target in myocardial ischaemia.

Topics: Adenosine Triphosphate; Animals; Calcium Signaling; Creatine Kinase; Creatine Kinase, Mitochondrial Form; Disease Models, Animal; Female; Isolated Heart Preparation; Magnetic Resonance Imaging, Cine; Male; Metabolomics; Mice, Inbred C57BL; Mice, Transgenic; Microscopy, Electron, Transmission; Mitochondria, Heart; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Myocardial Contraction; Myocardial Reperfusion Injury; Myocytes, Cardiac; Oxidative Phosphorylation; Phosphocreatine; Proton Magnetic Resonance Spectroscopy; Recovery of Function; Time Factors; Up-Regulation; Ventricular Function, Left

To observe the efficacy of phosphocreatine pre-administration (PCr-PA) on X-linked inhibitor of apoptosis protein (XIAP), the second mitochondia-derived activator of caspase (Smac) and apoptosis in the ischemic penumbra of rats with focal cerebral ischemia-reperfusion injury (CIRI).. A total of 60 healthy male Sprague Dawley (SD) rats were randomly divided into three groups (n=20): group A (the sham operation group), group B <intraperitoneally injected with 20 mg/kg (10 mg/ml) of saline before preparing the ischemia-reperfusion (IR) model>, and group C <intraperitoneally injected with 20 mg/kg (10 mg/ml) of PCr immediately before preparing the IR model>. After 24 h for reperfusion, the neurological function was evaluated and the tissue was sampled to detect expression of XIAP, Smac and caspase-3 positive cells in the ischemic penumbra so as to observe the apoptosis.. Compared with group B, neurological deficit scores, numbers of apoptotic cells, expression of Smac,caspase-9 and the numbers of Caspase-3 positive cells were decreased while expression of XIAP were increased in the ischemic penumbra of group C.. Phosphocreatine pre-administration may elicit neuroprotective effects in the brain by increasing expression of X-linked inhibitor of apoptosis protein, reducing expression of second mitochondia-derived activator of caspase, and inhibiting the apoptosis in the ischemic penumbra.

Topics: Animals; Apoptosis; Apoptosis Regulatory Proteins; Brain Ischemia; Cardiotonic Agents; Caspase 3; Disease Models, Animal; Drug Evaluation, Preclinical; Humans; Intracellular Signaling Peptides and Proteins; Male; Mitochondrial Proteins; Neuroprotective Agents; Phosphocreatine; Random Allocation; Rats; Rats, Sprague-Dawley; Reperfusion Injury; X-Linked Inhibitor of Apoptosis Protein

We performed metabolomic analyses of mouse brain using a transient middle cerebral artery occlusion (tMCAO) model with Matrix Assisted Laser Desorption/Ionization (MALDI)-mass spectrometry imaging (MSI) to reveal metabolite changes after cerebral ischemia. We selected and analyzed three metabolites, namely creatine (Cr), phosphocreatine (P-Cr), and ceramides (Cer), because these metabolites contribute to cell life and death. Eight-week-old male C57BL/6J mice were subjected to tMCAO via the intraluminal blockade of the middle cerebral artery (MCA) and reperfusion 60 min after the induction of ischemia. Each mouse was randomly assigned to one of the three groups; the groups were defined by the survival period after reperfusion: control, 1 h, and 24 h. Corrected samples were analyzed using MALDI-MSI. Results of MSI analysis showed the presence of several ionized substances and revealed spatial changes in some metabolites identified as precise substances, including Cr, P-Cr, Cer d18:1/18:0, phosphatidylcholine, L-glutamine, and L-histidine. Cr, P-Cr, and Cer d18:1/18:0 were changed after tMCAO, and P-Cr and Cer d18:1/18:0 accumulated over time in ischemic cores and surrounding areas following ischemia onset. The upregulation of P-Cr and Cer d18:1/18:0 was detected 1 h after tMCAO when no changes were evident on hematoxylin and eosin staining and immunofluorescence assay. P-Cr and Cer d18:1/18:0 can serve as neuroprotective therapies because they are biomarker candidates for cerebral ischemia.

Topics: Animals; Ceramides; Creatine; Disease Models, Animal; Infarction, Middle Cerebral Artery; Male; Metabolomics; Mice; Mice, Inbred C57BL; Phosphocreatine; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

Topics: Adenosine Triphosphate; Animals; Benzhydryl Compounds; Blood Glucose; Diabetes Mellitus; Disease Models, Animal; Energy Metabolism; Glucosides; Ketones; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Male; Mice, Inbred C57BL; Myocytes, Cardiac; Phosphocreatine; Sodium-Glucose Transporter 2 Inhibitors; Ventricular Function

Diabetes mellitus (DM) associated liver damage is a major health burden. Hepatocellular-damage in DM characterized with elevated endoplasmic reticulum stress (ER) and may enhanced insulin-resistance. Phosphocreatine (PCr) a rapidly high-energy-reserve molecule of phosphates naturally occurs in liver, brain and skeletal muscle. This study aimed to investigate the protective effect of PCr on the liver-injury-associated with DM and to report the mechanism involved. Wistar rat's diabetes model was induced using streptozotocin (STZ), and the animals were treated with 20 mg/kg, or 50 mg/kg PCr injection. Blood glucose level, and body wt were recorded. Liver tissues homogenate were analyzed for liver damage markers alanine transaminase (ALT), aspartate transaminase (AST). Liver tissues proteins further evaluated for apoptosis, endoplasmic reticulum stress (ER), and insulin resistance biomarkers using western blotting. Our results revealed that PCr reduced blood glucose level, improved body wt, ameliorates liver function enzymes. Furthermore, PCr upregulates anti-apoptotic Bcl2 proteins expression, and down-regulates significantly pro-apoptotic casp3 and Bax proteins expression in vivo and invitro. Moreover, ER stress CHOP, GRP78 and ATF4 biomarkers level were significantly attenuated in PCr treated animals comparing to STZ diabetes associated liver-damage model with significant improving in insulin-resistance Akt and IRS-1. Our results revealed that treating with PCr in diabetes-associated liver injury models decreased blood glucose level and possess protective effect in-vitro and in-vivo, which could be suggested as potential therapeutic strategy for diabetes associated liver injury patients.

Topics: Animals; Apoptosis; Biomarkers, Tumor; Blood Glucose; Body Weight; Carcinoma, Hepatocellular; Cell Shape; Cell Survival; Diabetes Mellitus, Experimental; Disease Models, Animal; Endoplasmic Reticulum Chaperone BiP; Endoplasmic Reticulum Stress; Hep G2 Cells; Humans; Insulin Resistance; Liver; Liver Neoplasms; Metabolome; Oxidative Stress; Phosphocreatine; Protective Agents; Rats, Wistar; Signal Transduction; Streptozocin

This study investigated whether the novel St. Thomas' Hospital polarizing cardioplegic solution (STH-POL) with esmolol/adenosine/magnesium offers improved myocardial protection by reducing demands for high-energy phosphates during cardiac arrest compared to the depolarizing St. Thomas' Hospital cardioplegic solution No 2 (STH-2).. Twenty anaesthetised pigs on tepid cardiopulmonary bypass were randomized to cardiac arrest for 60 min with antegrade freshly mixed, repeated, cold, oxygenated STH-POL or STH-2 blood cardioplegia every 20 min. Haemodynamic variables were continuously recorded. Left ventricular biopsies, snap-frozen in liquid nitrogen or fixed in glutaraldehyde, were obtained at Baseline, 58 min after cross-clamp and 20 and 180 min after weaning from bypass. Adenine nucleotides were evaluated by high-performance liquid chromatography, myocardial ultrastructure with morphometry.. With STH-POL myocardial creatine phosphate was increased compared to STH-2 at 58 min of cross-clamp [59.9 ± 6.4 (SEM) vs 44.5 ± 7.4 nmol/mg protein; P  <   0.025], and at 20 min after reperfusion (61.0 ± 6.7 vs 49.0 ± 5.5 nmol/mg protein; P  <   0.05), ATP levels were increased at 20 min of reperfusion with STH-POL (35.4 ± 1.1 vs 32.4 ± 1.2 nmol/mg protein; P  <   0.05). Mitochondrial surface-to-volume ratio was decreased with polarizing compared to depolarizing cardioplegia 20 min after reperfusion (6.74 ± 0.14 vs 7.46 ± 0.13 µm 2 /µm 3 ; P  =   0.047). None of these differences were present at 180 min of reperfusion. From 150 min of reperfusion and onwards, cardiac index was increased with STH-POL; 4.8 ± 0.2 compared to 4.0 ± 0.2 l/min/m 2 ( P  =   0.011) for STH-2 at 180 min.. Polarizing STH-POL cardioplegia improved energy status compared to standard STH-2 depolarizing blood cardioplegia during cardioplegic arrest and early after reperfusion.

Topics: Animals; Biopsy; Cardioplegic Solutions; Creatinine; Disease Models, Animal; Energy Metabolism; Female; Heart Arrest; Heart Arrest, Induced; Male; Myocardial Reperfusion Injury; Myocardium; Phosphocreatine; ROC Curve; Swine

Caspase-2 has features of both initiator and effector caspases. Previously, we have shown that brain hypoxia-induced production of caspases 1, 3, 8, and 9 is Src kinase mediated, a nonreceptor intracellular family of kinases. The present study tests the hypothesis that hypoxia results in increased expression of caspase-2 and this effect is mediated by Src kinase. Two to three days old newborn piglets were subjected to normoxia, hypoxia (Hx, FiO2 7%), and Src kinase inhibition (using PP2, 1 mg/kg, intravenous), followed by 30 min of acute hypoxia (Hx+PP2). ATP and phosphocreatine were determined biochemically to verify energy molecule depletion in the hypoxic groups. The cytosolic brain function was isolated and a western blot analysis was carried out using an antibody specific for the caspase-2. The immune-complex band density was expressed as OD/mm. Caspase-2 expression was increased two-fold in the Hx group. After Src kinase inhibition followed by hypoxia, caspase-2 expression was similar to normoxia levels. We conclude that hypoxia results in increased expression of caspase-2 protein in the cytosolic fraction of the cerebral cortex of the newborn piglets. This increase is mediated by Src kinase.

Topics: Adenosine Triphosphate; Animals; Animals, Newborn; Blotting, Western; Caspase 2; Cerebral Cortex; Cytosol; Disease Models, Animal; Hypoxia, Brain; Phosphocreatine; Protein Kinases; Pyrimidines; Spectrophotometry; src-Family Kinases; Swine

Cytosolic and mitochondrial creatine kinases (CK), through the creatine kinase-phosphocreatine (CK/PCr) system, provide a temporal and spatial energy buffer to maintain cellular energy homeostasis. However, the effects of bacterial infections on the kidney remain poorly understood and are limited only to histopathological analyses. Thus, the aim of this study was to investigate the involvement of cytosolic and mitochondrial CK activities in renal energetic homeostasis in silver catfish experimentally infected with Aeromonas caviae. Cytosolic CK activity decreased in infected animals, while mitochondrial CK activity increased compared to uninfected animals. Moreover, the activity of the sodium-potassium pump (Na

Topics: Adenosine Triphosphatases; Adenosine Triphosphate; Aeromonas caviae; Animals; Brazil; Catfishes; Creatine Kinase; Creatine Kinase, Mitochondrial Form; Cytosol; Disease Models, Animal; Energy Metabolism; Fish Diseases; Gram-Negative Bacterial Infections; Homeostasis; Kidney; Mitochondria; Phosphocreatine; Phosphorylation; Sodium-Potassium-Exchanging ATPase

Sickle cell disease (SCD) is associated with an impaired oxygen delivery to skeletal muscle that could alter ATP production processes. The present study aimed to determine the effects of sickle hemoglobin (HbS) on muscle pH homeostasis in response to exercise in homozygous (HbSS,

Topics: Acidosis; Anemia, Sickle Cell; Animals; Disease Models, Animal; Hemoglobin, Sickle; Homeostasis; Hydrogen-Ion Concentration; Magnetic Resonance Spectroscopy; Male; Mice; Muscle, Skeletal; Phosphocreatine; Physical Conditioning, Animal; Rest

The β3-adrenoceptor (β3-AR) is implicated in cardiac remodeling. Since metabolic dysfunction due to loss of mitochondria plays an important role in heart diseases, we examined the effects of β3-AR on mitochondrial biogenesis and energy metabolism in atrial fibrillation (AF).. Atrial fibrillation was created by rapid atrial pacing in adult rabbits. Rabbits were randomly divided into 4 groups: control, pacing (P7), β3-AR antagonist (L748337), and β3-AR agonist (BRL37344) groups. Atrial effective refractory period (AERP) and AF induction rate were measured. Atrial concentrations of adenine nucleotides and phosphocreatine were quantified through high-performance liquid chromatography. Mitochondrial DNA content was determined. Real-time polymerase chain reaction and Western blot were used to examine the expression levels of signaling intermediates related to mitochondrial biogenesis.. After pacing for 7 days, β3-AR was significantly upregulated, AERP was reduced, and the AF induction rate was increased. The total adenine nucleotides pool was significantly reduced due to the decrease in adenosine triphosphate (ATP). The P7 group showed decreased activity of F0F1-ATPase. Mitochondrial DNA content was decreased and mitochondrial respiratory chain subunits were downregulated after pacing. Furthermore, expression of transcription factors involved in mitochondrial biogenesis, including peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), nuclear respiratory factor 1 (NRF-1), and mitochondrial transcription factor A (Tfam), was lower in the P7 group in response to β3-AR activation. Further stimulation of β3-AR with BRL37344 exacerbated these effects, together with a significant decrease in the levels of phosphocreatine. In contrast, inhibition of β3-AR with L748337 partially restored mitochondrial biogenesis and energy metabolism of atria in the paced rabbits.. The activation of β3-AR contributes to atrial metabolic remodeling via transcriptional downregulation of PGC-1α/NRF-1/Tfam pathway that are involved in mitochondrial biogenesis, which ultimately perturbs mitochondrial function in rapid pacing-induced AF. The β3-AR is therefore a potential novel therapeutic target for the treatment or prevention of AF.

Topics: Adenine Nucleotides; Adrenergic beta-3 Receptor Agonists; Adrenergic beta-3 Receptor Antagonists; Animals; Anti-Arrhythmia Agents; Atrial Fibrillation; Atrial Function, Right; Atrial Remodeling; Cardiac Pacing, Artificial; Disease Models, Animal; DNA, Mitochondrial; Electron Transport Complex IV; Energy Metabolism; Female; Gene Expression Regulation; Heart Rate; Male; Mitochondria, Heart; Mitochondrial Proteins; NF-E2-Related Factor 1; Organelle Biogenesis; Phosphocreatine; Proton-Translocating ATPases; Rabbits; Receptors, Adrenergic, beta-3; Signal Transduction; Time Factors

Hypoxia-inducible factor (HIF) appears to function as a global master regulator of cellular and systemic responses to hypoxia. HIF pathway manipulation is of therapeutic interest; however, global systemic upregulation of HIF may have as yet unknown effects on multiple processes. We used a mouse model of Chuvash polycythemia (CP), a rare genetic disorder that modestly increases expression of HIF target genes in normoxia, to understand what these effects might be within the heart. An integrated in and ex vivo approach was employed. Compared with wild-type controls, CP mice had evidence (using in vivo magnetic resonance imaging) of pulmonary hypertension, right ventricular hypertrophy, and increased left ventricular ejection fraction. Glycolytic flux (measured using [(3)H]glucose) in the isolated contracting perfused CP heart was 1.8-fold higher. Net lactate efflux was 1.5-fold higher. Furthermore, in vivo (13)C-magnetic resonance spectroscopy (MRS) of hyperpolarized [(13)C1]pyruvate revealed a twofold increase in real-time flux through lactate dehydrogenase in the CP hearts and a 1.6-fold increase through pyruvate dehydrogenase. (31)P-MRS of perfused CP hearts under increased workload (isoproterenol infusion) demonstrated increased depletion of phosphocreatine relative to ATP. Intriguingly, no changes in cardiac gene expression were detected. In summary, a modest systemic dysregulation of the HIF pathway resulted in clear alterations in cardiac metabolism and energetics. However, in contrast to studies generating high HIF levels within the heart, the CP mice showed neither the predicted changes in gene expression nor any degree of LV impairment. We conclude that the effects of manipulating HIF on the heart are dose dependent.

Topics: Adenosine Triphosphate; Animals; Apoptosis Regulatory Proteins; Aryl Hydrocarbon Receptor Nuclear Translocator; Basic Helix-Loop-Helix Transcription Factors; Carbon Isotopes; Cardiotonic Agents; Disease Models, Animal; Glucose; Glycolysis; Heart; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia-Inducible Factor 1, alpha Subunit; Isolated Heart Preparation; Isoproterenol; L-Lactate Dehydrogenase; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Mice; Mutation; Myocardium; Phosphates; Phosphocreatine; Polycythemia; Pyruvic Acid; Repressor Proteins; Stroke Volume; Transcription Factors; Tritium; Von Hippel-Lindau Tumor Suppressor Protein

The study aims to characterize age-associated changes in skeletal muscle bioenergetics by evaluating the response to ischemia-reperfusion in the skeletal muscle of the Goto-Kakizaki (GK) rats, a rat model of non-obese type 2 diabetes (T2D). (31)P magnetic resonance spectroscopy (MRS) and blood oxygen level-dependent (BOLD) MRI was performed on the hindlimb of young (12 weeks) and adult (20 weeks) GK and Wistar (control) rats. (31)P-MRS and BOLD-MRI data were acquired continuously during an ischemia and reperfusion protocol to quantify changes in phosphate metabolites and muscle oxygenation. The time constant of phosphocreatine recovery, an index of mitochondrial oxidative capacity, was not statistically different between GK rats (60.8 ± 13.9 sec in young group, 83.7 ± 13.0 sec in adult group) and their age-matched controls (62.4 ± 11.6 sec in young group, 77.5 ± 7.1 sec in adult group). During ischemia, baseline-normalized BOLD-MRI signal was significantly lower in GK rats than in their age-matched controls. These results suggest that insulin resistance leads to alterations in tissue metabolism without impaired mitochondrial oxidative capacity in GK rats.

Topics: Animals; Brain Ischemia; Diabetes Mellitus, Type 2; Disease Models, Animal; Hydrogen-Ion Concentration; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Male; Mitochondria; Muscle, Skeletal; Phosphocreatine; Phosphorus Radioisotopes; Rats; Reperfusion Injury

Seizures and neurologic involvement have been reported in patients infected with Shiga toxin (Stx) producing

Topics: Amygdala; Animals; Brain; Calcium-Binding Proteins; Cell Culture Techniques; Cerebral Cortex; Disease Models, Animal; DNA-Binding Proteins; Endothelial Cells; Erythrocytes; Escherichia coli; Hemolytic-Uremic Syndrome; Hippocampus; Humans; Kidney; Magnetic Resonance Imaging; Male; Mice; Microfilament Proteins; Microglia; Nervous System; Phosphocreatine; Rabbits; Repressor Proteins; Shiga Toxin; Shiga Toxin 2; Spectrum Analysis; Thalamus; Toxicity Tests; Tumor Necrosis Factor-alpha; Weight Gain; Weight Loss

To explore the role of uncoupling protein 2 (UCP2) during myocardial dysfunction in a canine model of endotoxin shock, 26 mongrel canines were randomly divided into the following four groups: A (control group; n = 6), B2 (shock after 2 h; n = 7), B4 (shock after 4 h; n = 7), and B6 (shock after 6 h; n = 6). Escherichia coli endotoxin was injected into the canines via the central vein, and hemodynamics were monitored. Energy metabolism, UCP2 mRNA and protein expression, and UCP2 localization were analyzed, and the correlation between energy metabolism changes, and UCP2 expression was determined. After the canine endotoxin shock model was successfully established, the expression of UCP2 mRNA and protein was found to increase, with later time points showing significant increases (P < 0.05). Immunofluorescence assays of UCP2 in heart tissue showed that UCP2 was localized in the cytoplasm, and its expression pattern was the same as that found in the mRNA and protein analyses. The energy metabolism results revealed that the ADP levels increased, but the ATP and phosphocreatine (PCr) levels and ATP/ADP and PCr/ATP ratios decreased in the model. In particular, the PCr/ATP ratio was significantly different from that of the control group 6 h after shock (P < 0.05). Furthermore, correlation analysis showed that the UCP2 protein and mRNA levels were negatively correlated with myocardial energy levels. In summary, decreased energy synthesis can occur in the myocardium during endotoxin shock, and UCP2 may play an important role in this process. The negative correlation between UCP2 expression and energy metabolism requires further study, as the results might contribute to the treatment of sepsis with heart failure.

Topics: Adenosine Triphosphate; Animals; Disease Models, Animal; Dogs; Energy Metabolism; Female; Immunohistochemistry; Ion Channels; Male; Mitochondrial Proteins; Myocardium; Phosphocreatine; RNA, Messenger; Shock, Septic; Uncoupling Protein 2

Conventional MRI is frequently used during the diagnosis of multiple sclerosis but provides only little additional pathological information. Proton MRS ((1) H-MRS), however, provides biochemical information on the lesion pathology by visualization of a spectrum of metabolites. In this study we aimed to better understand the changes in metabolite concentrations following demyelination of the white matter. Therefore, we used the cuprizone model, a well-established mouse model to mimic type III human multiple sclerosis demyelinating lesions. First, we identified CX3 CL1/CX3 CR1 signaling as a major regulator of microglial activity in the cuprizone mouse model. Compared with control groups (heterozygous CX3 CR1(+/-) C57BL/6 mice and wild type CX3 CR1(+/+) C57BL/6 mice), microgliosis, astrogliosis, oligodendrocyte cell death and demyelination were shown to be highly reduced or absent in CX3 CR1(-/-) C57BL/6 mice. Second, we show that (1) H-MRS metabolite spectra are different when comparing cuprizone-treated CX3 CR1(-/-) mice showing mild demyelination with cuprizone-treated CX3 CR1(+/+) mice showing severe demyelination and demyelination-associated inflammation. Following cuprizone treatment, CX3 CR1(+/+) mice show a decrease in the Glu, tCho and tNAA concentrations as well as an increased Tau concentration. In contrast, following cuprizone treatment CX3 CR1(-/-) mice only showed a decrease in tCho and tNAA concentrations. Therefore, (1) H-MRS might possibly allow us to discriminate demyelination from demyelination-associated inflammation via changes in Tau and Glu concentration. In addition, the observed decrease in tCho concentration in cuprizone-induced demyelinating lesions should be further explored as a possible diagnostic tool for the early identification of human MS type III lesions.

Topics: Animals; Aspartic Acid; Brain Chemistry; Choline; Creatine; Cuprizone; Demyelinating Diseases; Dipeptides; Disease Models, Animal; Female; Gliosis; Magnetic Resonance Imaging; Male; Mice; Mice, Inbred C57BL; Neuroimaging; Oligodendroglia; Phosphocreatine; Proton Magnetic Resonance Spectroscopy

Maintenance of cerebral viability and function is an important goal of critical care in victims of injury due to ischemia and hypovolemia. As part of the multiple organ dysfunction syndrome, the brain function after trauma is influenced by the systemic inflammatory response. We investigated the effect of EF24, an anti-inflammatory bis-chalcone, on cerebral bioenergetics in a rat model of 45% hemorrhagic shock. The rats were treated with EF24 (0.4 mg/kg) or EF24 with an artificial oxygen carrier liposome-encapsulated hemoglobin (LEH). The volume of LEH administered was equal to the shed blood. The brain was collected after 6 h of shock for biochemical assays. EF24 treatment showed significant recovery of ATP, phosphocreatine, and NAD/NADH ratio. It also increased citrate synthase activity and cytochrome c oxidase subunit IV expression which were reduced in shock brain. Furthermore, it reduced the shock-induced accumulation of pyruvate and pyruvate dehydrogenase kinase-1 expression, suggesting that EF24 treatment improves cerebral energetics by restoring perturbed pyruvate metabolism in the mitochondria. These effects of EF24 were associated with reduced poly(ADP-ribose) polymerase cleavage and a significant improvement in the levels of nerve growth factor and brain-derived neurotrophic factor in shock brain. Co-administration of LEH with EF24 was only marginally more effective as compared to the treatment with EF24 alone. These results show that EF24 treatment sets up a pro-survival phenotype in shock by resurrecting cerebral bioenergetics. Since EF24 was effective in the absence of accompanying fluid resuscitation, it has potential utility as a pre-hospital pharmacotherapy in shock due to accidental blood loss.

Topics: Adenosine Triphosphate; Animals; Benzylidene Compounds; Brain; Brain-Derived Neurotrophic Factor; Disease Models, Animal; Energy Metabolism; Male; Mitochondria; NAD; Nerve Growth Factor; Neuroprotective Agents; Phosphocreatine; Piperidones; Pyruvic Acid; Rats, Sprague-Dawley; Shock, Hemorrhagic

The interleukin-10 knockout mouse (IL10(tm/tm)) has been proposed as a model for human frailty, a geriatric syndrome characterized by skeletal muscle (SM) weakness, because it develops an age-related decline in SM strength compared to control (C57BL/6J) mice. Compromised energy metabolism and energy deprivation appear to play a central role in muscle weakness in metabolic myopathies and muscular dystrophies. Nonetheless, it is not known whether SM energy metabolism is altered in frailty. A combination of in vivo (31)P nuclear magnetic resonance experiments and biochemical assays was used to measure high-energy phosphate concentrations, the rate of ATP synthesis via creatine kinase (CK), the primary energy reserve reaction in SM, as well as the unidirectional rates of ATP synthesis from inorganic phosphate (Pi) in hind limb SM of 92-week-old control (n = 7) and IL10(tm/tm) (n = 6) mice. SM Phosphocreatine (20.2 ± 2.3 vs. 16.8 ± 2.3 μmol/g, control vs. IL10(tm/tm), p < 0.05), ATP flux via CK (5.0 ± 0.9 vs. 3.1 ± 1.1 μmol/g/s, p < 0.01), ATP synthesis from inorganic phosphate (Pi → ATP) (0.58 ± 0.3 vs. 0.26 ± 0.2 μmol/g/s, p < 0.05) and the free energy released from ATP hydrolysis (∆G ∼ATP) were significantly lower and [Pi] (2.8 ± 1.0 vs. 5.3 ± 2.0 μmol/g, control vs. IL10(tm/tm), p < 0.05) markedly higher in IL10(tm/tm) than in control mice. These observations demonstrate that, despite normal in vitro metabolic enzyme activities, in vivo SM ATP kinetics, high-energy phosphate levels and energy release from ATP hydrolysis are reduced and inorganic phosphate is elevated in a murine model of frailty. These observations do not prove, but are consistent with the premise, that energetic abnormalities may contribute metabolically to SM weakness in this geriatric syndrome.

Topics: Adenosine Triphosphate; Aging; Animals; Creatine Kinase; Disease Models, Animal; Energy Metabolism; Hydrolysis; Kinetics; Magnetic Resonance Spectroscopy; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Muscle Weakness; Muscle, Skeletal; Phenotype; Phosphocreatine

The pharmacokinetic (PK) studies of phosphocreatine (PCr) and its active metabolite creatine (Cr) are considerably lacking. This study is to comparatively investigate the PK profiles of PCr and Cr in mice plasma and myocardium as well as the ATP level.. After iv administration of equimolar PCr and preformed Cr to healthy and Pit-induced myocardial ischemic mice, plasma and myocardium samples were analyzed for exogenous PCr, Cr and related ATP concentrations using a specific ion-pair reversed-phase HPLC-UV assay.. The plasma C-T data of iv PCr and Cr were well fitted to two-compartment model. Following iv PCr, Cr appeared in plasma as early as 1.0 min postdose with a longer t1/2 than PCr and had a fm of 72%. The mice dosed iv PCr preceded 5 min by ip Pit 30 U/kg showed longer t1/2β PCr and t1/2 Cr in plasma and elevated Cmax, Cr and Cmax, ATP in myocardium compared with mice dosed iv PCr alone, and it was estimated that about 40% ATP produced by iv PCr was from Cr.. The PCr in plasma is converted to Cr rapidly and mostly, and shows an elimination rate limited (ERL) metabolite disposition. Iv PCr caused a significantly elevated and long-lasing myocardial ATP and Cr levels. The Pit-induced myocardial ischemia brings slower elimination of PCr and Cr and higher peak concentrations of Cr and ATP in myocardium. The metabolite Cr at least partially mediates PCr-caused rise in myocardial ATP level and also possibly the cardio-protective effects of PCr.

Topics: Adenosine Triphosphate; Animals; Chromatography, High Pressure Liquid; Creatine; Disease Models, Animal; Half-Life; Male; Mice; Myocardial Ischemia; Myocardium; Phosphocreatine; Pituitary Hormones, Posterior; Spectrophotometry, Ultraviolet

There is growing evidence that alterations in metabolism may contribute to tumorigenesis. Here, we report on members of families with the Li-Fraumeni syndrome who carry germline mutations in TP53, the gene encoding the tumor-suppressor protein p53. As compared with family members who are not carriers and with healthy volunteers, family members with these mutations have increased oxidative phosphorylation of skeletal muscle. Basic experimental studies of tissue samples from patients with the Li-Fraumeni syndrome and a mouse model of the syndrome support this in vivo finding of increased mitochondrial function. These results suggest that p53 regulates bioenergetic homeostasis in humans. (Funded by the National Heart, Lung, and Blood Institute and the National Institutes of Health; ClinicalTrials.gov number, NCT00406445.).

Topics: Animals; Case-Control Studies; Disease Models, Animal; Energy Metabolism; Exercise; Female; Genes, p53; Germ-Line Mutation; Heterozygote; Humans; Li-Fraumeni Syndrome; Male; Mice; Mitochondria, Muscle; Muscle, Skeletal; Oxygen Consumption; Phosphocreatine; Pilot Projects; Weight Lifting

Connexin 43 (Cx43) deficiency increases myocardial tolerance to ischemia-reperfusion injury and abolishes preconditioning protection. It is not known whether modifications in baseline signaling through protective RISK or SAFE pathways or in response to preconditioning may contribute to these effects. To answer this question we used Cx43(Cre-ER(T)/fl) mice, in which Cx43 expression is abolished after 4-hydroxytamoxifen (4-OHT) administration. Isolated hearts from Cx43(Cre-ER(T)/fl) mice, or from Cx43(fl/fl) controls, treated with vehicle or 4-OHT, were submitted to global ischemia (40 min) and reperfusion. Cx43 deficiency was associated with reduced infarct size after ischemia-reperfusion (11.17 ± 3.25 % vs. 65.04 ± 3.79, 59.31 ± 5.36 and 65.40 ± 4.91, in Cx43(fl/fl) animals treated with vehicle, Cx43(fl/fl) mice treated with 4-OHT, and Cx43(Cre-ER(T)/fl) mice treated with vehicle, respectively, n = 8-9, p < 0.001). However, the ratio phosphorylated/total protein expression for Akt, ERK-1/2, GSK3β and STAT3 was not increased in normoxic samples from animals lacking Cx43. Instead, a reduction in the phosphorylation state of GSK3β was observed in Cx43-deficient mice (ratio: 0.15 ± 0.02 vs. 0.56 ± 0.11, 0.77 ± 0.15, and 0.46 ± 0.14, respectively, n = 5-6, p < 0.01). Furthermore, ischemic preconditioning (IPC, 4 cycles of 3.5 min of ischemia and 5 min of reperfusion) increased phosphorylation of ERK-1/2, GSK3β, and STAT3 in all hearts without differences between groups (n = 5-6, p < 0.05), although Cx43 deficient mice were not protected by either IPC or pharmacological preconditioning with diazoxide. Our data demonstrate that modification of RISK and SAFE signaling does not contribute to the role of Cx43 in the increased tolerance to myocardial ischemia-reperfusion injury and in preconditioning protection.

Topics: Adenosine Triphosphate; Animals; Cell Death; Connexin 43; Disease Models, Animal; Energy Metabolism; Enzyme Activation; Female; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Ischemic Preconditioning, Myocardial; Magnetic Resonance Spectroscopy; Male; Mice; Mice, 129 Strain; Mice, Inbred C57BL; Mice, Knockout; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Phosphocreatine; Phosphorylation; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Signal Transduction; STAT3 Transcription Factor; Time Factors; Ventricular Function, Left; Ventricular Pressure

Cardiac hypertrophy is accompanied by significant alterations in energy metabolism. Whether these changes in energy metabolism precede and contribute to the development of heart failure in the hypertrophied heart is not clear.. Mice were subjected to cardiac hypertrophy secondary to pressure-overload as a result of an abdominal aortic constriction (AAC). The rates of energy substrate metabolism were assessed in isolated working hearts obtained 1, 2, and 3 weeks after AAC. Mice subjected to AAC demonstrated a progressive development of cardiac hypertrophy. In vivo assessment of cardiac function (via echocardiography) demonstrated diastolic dysfunction by 2 weeks (20% increase in E/E'), and systolic dysfunction by 3 weeks (16% decrease in % ejection fraction). Marked cardiac insulin-resistance by 2 weeks post-AAC was evidenced by a significant decrease in insulin-stimulated rates of glycolysis and glucose oxidation, and plasma membrane translocation of glucose transporter 4. Overall ATP production rates were decreased at 2 and 3 weeks post-AAC (by 37% and 47%, respectively) because of a reduction in mitochondrial oxidation of glucose, lactate, and fatty acids that was not accompanied by an increase in myocardial glycolysis rates. Reduced mitochondrial complex V activity was evident at 3 weeks post-AAC, concomitant with a reduction in the ratio of phosphocreatine to ATP.. The development of cardiac insulin-resistance and decreased mitochondrial oxidative metabolism are early metabolic changes in the development of cardiac hypertrophy, which create an energy deficit that may contribute to the progression from hypertrophy to heart failure.

Topics: Adenosine Triphosphate; Animals; Aorta, Abdominal; Arterial Pressure; Blood Glucose; Cardiomegaly; Disease Models, Animal; Disease Progression; Energy Metabolism; Fatty Acids; Glucose Transporter Type 4; Glycolysis; Heart Failure, Systolic; Insulin; Insulin Resistance; Lactic Acid; Ligation; Male; Mice; Mice, Inbred C57BL; Mitochondria, Heart; Mitochondrial Proton-Translocating ATPases; Myocardium; Oxidation-Reduction; Phosphocreatine; Stroke Volume; Time Factors; Ventricular Function, Left; Ventricular Pressure

Impaired energy metabolism has been implicated in the pathogenesis of heart failure. Hyperpolarized (13)C magnetic resonance (MR), in which (13)C-labelled metabolites are followed using MR imaging (MRI) or spectroscopy (MRS), has enabled non-invasive assessment of pyruvate metabolism. We investigated the hypothesis that if we serially examined a model of heart failure using non-invasive hyperpolarized [(13)C]pyruvate with MR, the profile of in vivo pyruvate oxidation would change throughout the course of the disease.. Dilated cardiomyopathy (DCM) was induced in pigs (n = 5) by rapid pacing. Pigs were examined using MR at weekly time points: cine-MRI assessed cardiac structure and function; hyperpolarized [2-(13)C]pyruvate was administered intravenously, and (13)C MRS monitored [(13)C]glutamate production; (31)P MRS assessed cardiac energetics [phosphocreatine (PCr)/ATP]; and hyperpolarized [1-(13)C]pyruvate was administered for MRI of pyruvate dehydrogenase complex (PDC)-mediated pyruvate oxidation via [(13)C]bicarbonate production. Early in pacing, the cardiac index decreased by 25%, PCr/ATP decreased by 26%, and [(13)C]glutamate production decreased by 51%. After clinical features of DCM appeared, end-diastolic volume increased by 40% and [(13)C]bicarbonate production decreased by 67%. Pyruvate dehydrogenase kinase 4 protein increased by two-fold, and phosphorylated Akt decreased by half. Peroxisome proliferator-activated receptor-α and carnitine palmitoyltransferase-1 gene expression decreased by a half and a third, respectively.. Despite early changes associated with cardiac energetics and (13)C incorporation into the Krebs cycle, pyruvate oxidation was maintained until DCM developed, when the heart's capacity to oxidize both pyruvate and fats was reduced. Hyperpolarized (13)C MR may be important to characterize metabolic changes that occur during heart failure progression.

Topics: Adenosine Triphosphate; Animals; Bicarbonates; Carbon Isotopes; Cardiac Pacing, Artificial; Cardiac Volume; Cardiomyopathy, Dilated; Carnitine O-Palmitoyltransferase; Citric Acid Cycle; Disease Models, Animal; Energy Metabolism; Gene Expression; Glutamic Acid; Glycolysis; Heart Failure; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Membrane Transport Proteins; Phosphocreatine; PPAR alpha; Protein Kinases; Pyruvate Dehydrogenase Complex; Pyruvic Acid; Swine; Ventricular Dysfunction, Left

The mechanisms by which ischemic preconditioning (IP) inhibits mitochondrial permeability transition pore opening and, hence, ischemia-reperfusion injury remain unclear. Here we investigate whether and how mitochondria-bound hexokinase 2 (mtHK2) may exert part of the cardioprotective effects of IP.. Control and IP Langendorff-perfused rat hearts were subject to ischemia and reperfusion with measurement of hemodynamic function and infarct size. Outer mitochondrial membrane (OMM) permeabilization after ischemia was determined by measuring rates of respiration and H2O2 production in the presence and absence of added cytochrome c in isolated mitochondria and permeabilized fibers. IP prevented OMM permeabilization during ischemia and reduced the loss of mtHK2, but not Bcl-xL, observed in control ischemic hearts. By contrast, treatment of permeabilized fibers with glucose-6-phosphate at pH 6.3 induced mtHK2 loss without OMM permeabilization. However, metabolic pretreatments of the perfused heart chosen to modulate glucose-6-phosphate and intracellular pHi revealed a strong inverse correlation between end-ischemic mtHK2 content and infarct size after reperfusion. Loss of mtHK2 was also associated with reduced rates of creatine phosphate generation during the early phase of reperfusion. This could be mimicked in permeabilized fibers after mtHK2 dissociation.. We propose that loss of mtHK2 during ischemia destabilizes mitochondrial contact sites, which, when accompanied by degradation of Bcl-xL, induces OMM permeabilization and cytochrome c loss. This stimulates reactive oxygen species production and mitochondrial permeability transition pore opening on reperfusion, leading to infarction. Consequently, inhibition of mtHK2 loss during ischemia could be an important mechanism responsible for the cardioprotection mediated by IP and other pretreatments.

Topics: Animals; bcl-2-Associated X Protein; bcl-X Protein; Cytochromes c; Disease Models, Animal; Glucose-6-Phosphate; Hemodynamics; Hexokinase; Hydrogen Peroxide; Ischemic Preconditioning, Myocardial; Male; Mitochondria, Heart; Mitochondrial Membrane Transport Proteins; Mitochondrial Membranes; Mitochondrial Permeability Transition Pore; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Permeability; Phosphocreatine; Rats; Rats, Wistar; Reactive Oxygen Species

Brain energy deficit has been a suggested cause of Huntington disease (HD), but ATP depletion has not reliably been shown in preclinical models, possibly because of the immediate post-mortem changes in cellular energy metabolism. To examine a potential role of a low energy state in HD, we measured, for the first time in a neurodegenerative model, brain levels of high energy phosphates using microwave fixation, which instantaneously inactivates brain enzymatic activities and preserves in vivo levels of analytes. We studied HD transgenic R6/2 mice at ages 4, 8, and 12 weeks. We found significantly increased creatine and phosphocreatine, present as early as 4 weeks for phosphocreatine, preceding motor system deficits and decreased ATP levels in striatum, hippocampus, and frontal cortex of R6/2 mice. ATP and phosphocreatine concentrations were inversely correlated with the number of CAG repeats. Conversely, in mice injected with 3-nitroproprionic acid, an acute model of brain energy deficit, both ATP and phosphocreatine were significantly reduced. Increased creatine and phosphocreatine in R6/2 mice was associated with decreased guanidinoacetate N-methyltransferase and creatine kinase, both at the protein and RNA levels, and increased phosphorylated AMP-dependent protein kinase (pAMPK) over AMPK ratio. In addition, in 4-month-old knock-in Hdh(Q111/+) mice, the earliest metabolic alterations consisted of increased phosphocreatine in the frontal cortex and increased the pAMPK/AMPK ratio. Altogether, this study provides the first direct evidence of chronic alteration in homeostasis of high energy phosphates in HD models in the earliest stages of the disease, indicating possible reduced utilization of the brain phosphocreatine pool.

Topics: Adenosine Triphosphate; Animals; Brain Chemistry; Convulsants; Disease Models, Animal; Energy Metabolism; Frontal Lobe; Gene Knock-In Techniques; Guanidinoacetate N-Methyltransferase; Huntington Disease; Mice; Mice, Transgenic; Nerve Tissue Proteins; Nitro Compounds; Phosphocreatine; Propionates

The normal heart relies primarily on the oxidation of fatty acids (FA) for ATP production, whereas during heart failure (HF) glucose utilization increases, implying pathological changes to cardiac energy metabolism. Despite the noted lipotoxic effects of elevating FA, our work has demonstrated a cardioprotective effect of a high fat diet (SAT) when fed after myocardial infarction (MI), as compared to normal chow (NC) fed cohorts. This data has suggested a mechanistic link to energy metabolism. The goal of this study was to determine the impact of SAT on the metabolic phenotype of the heart after MI. Male Wistar rats underwent coronary ligation surgery (MI) and were evaluated after 8 weeks of SAT. Induction of MI was verified by echocardiography. LV function assessed by in vivo hemodynamic measurements revealed improvements in the MI-SAT group as compared to MI-NC. Perfused working hearts revealed a decrease in cardiac work in MI-NC that was improved in MI-SAT. Glucose oxidation was increased and FA oxidation decreased in MI-NC compared to shams suggesting an alteration in the metabolic profile that was ameliorated by SAT. (31)P NMR analysis of Langendorff perfused hearts revealed no differences in PCr:ATP indicating no overt energy deficit in MI groups. Phospho-PDH and PDK(4) were increased in MI-SAT, consistent with a shift towards fatty acid oxidation (FAO). Overall, these results support the hypothesis that SAT post-infarction promotes a normal metabolic phenotype that may serve a cardioprotective role in the injured heart.

Topics: Adenosine Triphosphate; Animals; Diet, High-Fat; Disease Models, Animal; Echocardiography; Energy Metabolism; Hemodynamics; Male; Metabolome; Myocardial Infarction; Myocardium; Phenotype; Phosphocreatine; Phosphorylation; Protein Kinases; Pyruvate Dehydrogenase Complex; Rats

The effect of citoflavin and neoton preparations on the migration activity of neutrophil granulocytes under action of mitogen-induced immunocompetent blood cells, Peyer's patches, spleen and inguinal lymph was studied on a group of 55 male chinchilla rabbits with experimental model of widespread purulent peritonitis. It is established that the regulating action of immunocompetent cells on the migration of neutrophil leukocytes under the conditions of widespread purulent peritonitis is stable and widespread process, which is observed within 5 days of the postoperative period. The use of citoflavin and neoton during the postoperative period produces correction of the activity of immunocompetent cells, changing their properties in regulation of the migratory activity of neutrophil granulocytes. The effect is characteristic of both preparations and it is observed in all investigated organs, being manifested to a greater degree in immunocompetent cells of peripheral blood and Peyer's patches. Metabolic preparation citoflavin exhibits a more pronounced immunotropic action in comparison to neoton, which contains creatine phosphate.

Topics: Animals; Cardiotonic Agents; Cell Movement; Disease Models, Animal; Drug Combinations; Escherichia coli; Flavin Mononucleotide; Groin; Humans; Inosine Diphosphate; Lymph Nodes; Lymphocytes; Male; Monocytes; Neuroprotective Agents; Neutrophils; Niacinamide; Peritonitis; Peyer's Patches; Phosphocreatine; Postoperative Period; Rabbits; Spleen; Succinates; Suppuration

Structural changes in the heart are studied at an experimental widespread purulent peritonitis. It was established that in 6 hours after initiation of peritonitis in a myocardium the severe disorders of blood circulation, interstitial edema, the phenomena of kariopyknosis, development of systemic toxic damages specifying in high speed at this disease were observed. One of the mechanism of their development is a energy deficiency. The proof of this is destructive changes of cardiomyocytes mitochondria. The comparative analysis of use of metabolic preparations "Citoflavin", containing amber acid, and "Neoton", containing phosphocreatine, for the purpose of pharmacological support of cardiac activity at an experimental widespread purulent peritonitis has revealed high efficiency of the preparation "Citoflavin". It caused more intensive decrease of inflammatory changes in a myocardium, preventing of cardiomyocytes necrobiosis, contribution to preservation of normal structure and growth of quantity of mitochondria.

Topics: Animals; Cardiotonic Agents; Disease Models, Animal; Heart Diseases; Mitochondria, Heart; Myocardium; Organs at Risk; Peritonitis; Phosphocreatine; Photomicrography; Rabbits; Severity of Illness Index; Suppuration; Treatment Outcome

The mechanism by which endogenous progenitor cells contribute to functional and beneficial effects in stem cell therapy remains unknown.. Utilizing a novel (31)P magnetic resonance spectroscopy-2-dimensional chemical shift imaging method, this study examined the heterogeneity and bioenergetic consequences of postinfarction left ventricular (LV) remodeling and the mechanisms of endogenous progenitor cell contribution to the cellular therapy.. Human embryonic stem cell-derived vascular cells (hESC-VCs) that stably express green fluorescent protein and firefly luciferase (GFP(+)/Luc(+)) were used for the transplantation. hESC-VCs may release various cytokines to promote angiogenesis, prosurvival, and antiapoptotic effects. Both in vitro and in vivo experiments demonstrated that hESC-VCs effectively inhibit myocyte apoptosis. In the mouse model, a fibrin patch-based cell delivery resulted in a significantly better cell engraftment rate that was accompanied by a better ejection fraction. In the swine model of ischemia-reperfusion, the patch-enhanced delivery of hESC-VCs resulted in alleviation of abnormalities including border zone myocardial perfusion, contractile dysfunction, and LV wall stress. These results were also accompanied by a pronounced recruitment of endogenous c-kit(+) cells to the injury site. These improvements were directly associated with a remarkable improvement in myocardial energetics, as measured by a novel in vivo (31)P magnetic resonance spectroscopy-2-dimensional chemical shift imaging technology.. The findings of this study demonstrate that a severely abnormal heterogeneity of myocardial bioenergetics in hearts with postinfarction LV remodeling can be alleviated by the hESC-VCs therapy. These findings suggest an important therapeutic target of peri-scar border zone and a promising therapeutic potential for using hESC-VCs together with the fibrin patch-based delivery system.

Topics: Adenosine Triphosphate; Animals; Apoptosis; Cell Line; Cell Movement; Cell Tracking; Coronary Circulation; Disease Models, Animal; Embryonic Stem Cells; Endothelial Cells; Energy Metabolism; Female; Fibrin; Green Fluorescent Proteins; Humans; Hypertrophy, Left Ventricular; Luciferases, Firefly; Magnetic Resonance Spectroscopy; Mice; Mice, Inbred NOD; Mice, SCID; Myocardial Contraction; Myocardial Infarction; Myocardium; Myocytes, Cardiac; Myocytes, Smooth Muscle; Phosphocreatine; Proto-Oncogene Proteins c-kit; Recovery of Function; Stem Cell Transplantation; Stroke Volume; Swine; Time Factors; Tissue Scaffolds; Transfection; Ventricular Function, Left; Ventricular Remodeling

The second-largest cause of X-linked mental retardation is a deficiency in creatine transporter (CRT; encoded by SLC6A8), which leads to speech and language disorders with severe cognitive impairment. This syndrome, caused by the absence of creatine in the brain, is currently untreatable because CRT is required for creatine entry into brain cells. Here, we developed a brain-specific Slc6a8 knockout mouse (Slc6a8-/y) as an animal model of human CRT deficiency in order to explore potential therapies for this syndrome. The phenotype of the Slc6a8-/y mouse was comparable to that of human patients. We successfully treated the Slc6a8-/y mice with the creatine analog cyclocreatine. Brain cyclocreatine and cyclocreatine phosphate were detected after 9 weeks of cyclocreatine treatment in Slc6a8-/y mice, in contrast to the same mice treated with creatine or placebo. Cyclocreatine-treated Slc6a8-/y mice also exhibited a profound improvement in cognitive abilities, as seen with novel object recognition as well as spatial learning and memory tests. Thus, cyclocreatine appears promising as a potential therapy for CRT deficiency.

Topics: Animals; Base Sequence; Brain; Cognition; Cognition Disorders; Creatinine; Disease Models, Animal; DNA Primers; Female; Humans; Imidazolidines; Learning; Male; Membrane Transport Proteins; Memory; Mental Retardation, X-Linked; Mice; Mice, Inbred C57BL; Mice, Knockout; Models, Neurological; Phosphocreatine

Reduced myofibrillar ATP availability during prolonged myocardial ischemia may limit post-ischemic mechanical function. Because creatine kinase (CK) is the prime energy reserve reaction of the heart and because it has been difficult to augment ATP synthesis during and after ischemia, we used mice that overexpress the myofibrillar isoform of creatine kinase (CKM) in cardiac-specific, conditional fashion to test the hypothesis that CKM overexpression increases ATP delivery in ischemic-reperfused hearts and improves functional recovery. Isolated, retrograde-perfused hearts from control and CKM mice were subjected to 25 min of global, no-flow ischemia and 40 min of reperfusion while cardiac function [rate pressure product (RPP)] was monitored. A combination of (31)P-nuclear magnetic resonance experiments at 11.7T and biochemical assays was used to measure the myocardial rate of ATP synthesis via CK (CK flux) and intracellular pH (pH(i)). Baseline CK flux was severalfold higher in CKM hearts (8.1 ± 1.0 vs. 32.9 ± 3.8, mM/s, control vs. CKM; P < 0.001) with no differences in phosphocreatine concentration [PCr] and RPP. End-ischemic pH(i) was higher in CKM hearts than in control hearts (6.04 ± 0.12 vs. 6.37 ± 0.04, control vs. CKM; P < 0.05) with no differences in [PCr] and [ATP] between the two groups. Post-ischemic PCr (66.2 ± 1.3 vs. 99.1 ± 8.0, %preischemic levels; P < 0.01), CK flux (3.2 ± 0.4 vs. 14.0 ± 1.2 mM/s; P < 0.001) and functional recovery (13.7 ± 3.4 vs. 64.9 ± 13.2%preischemic RPP; P < 0.01) were significantly higher and lactate dehydrogenase release was lower in CKM than in control hearts. Thus augmenting cardiac CKM expression attenuates ischemic acidosis, reduces injury, and improves not only high-energy phosphate content and the rate of CK ATP synthesis in postischemic myocardium but also recovery of contractile function.

Topics: Acidosis; Adenosine Triphosphate; Animals; Creatine Kinase, MM Form; Disease Models, Animal; Energy Metabolism; Hydrogen-Ion Concentration; Kinetics; L-Lactate Dehydrogenase; Magnetic Resonance Spectroscopy; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Myocardial Contraction; Myocardial Ischemia; Myocardial Reperfusion Injury; Myocardium; Phosphocreatine; Up-Regulation

Increasing energy storage capacity by elevating creatine and phosphocreatine (PCr) levels to increase ATP availability is an attractive concept for protecting against ischaemia and heart failure. However, testing this hypothesis has not been possible since oral creatine supplementation is ineffectual at elevating myocardial creatine levels. We therefore used mice overexpressing creatine transporter in the heart (CrT-OE) to test for the first time whether elevated creatine is beneficial in clinically relevant disease models of heart failure and ischaemia/reperfusion (I/R) injury.. CrT-OE mice were selected for left ventricular (LV) creatine 20-100% above wild-type values and subjected to acute and chronic coronary artery ligation. Increasing myocardial creatine up to 100% was not detrimental even in ageing CrT-OE. In chronic heart failure, creatine elevation was neither beneficial nor detrimental, with no effect on survival, LV remodelling or dysfunction. However, CrT-OE hearts were protected against I/R injury in vivo in a dose-dependent manner (average 27% less myocardial necrosis) and exhibited greatly improved functional recovery following ex vivo I/R (59% of baseline vs. 29%). Mechanisms contributing to ischaemic protection in CrT-OE hearts include elevated PCr and glycogen levels and improved energy reserve. Furthermore, creatine loading in HL-1 cells did not alter antioxidant defences, but delayed mitochondrial permeability transition pore opening in response to oxidative stress, suggesting an additional mechanism to prevent reperfusion injury.. Elevation of myocardial creatine by 20-100% reduced myocardial stunning and I/R injury via pleiotropic mechanisms, suggesting CrT activation as a novel, potentially translatable target for cardiac protection from ischaemia.

Topics: Animals; Cell Line; Creatine; Disease Models, Animal; Energy Metabolism; Glycogen; Heart Failure; Magnetic Resonance Imaging, Cine; Membrane Transport Proteins; Mice; Mice, Inbred C57BL; Mice, Transgenic; Mitochondria, Heart; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardial Stunning; Myocardium; Necrosis; Oxidative Stress; Phosphocreatine; Time Factors; Up-Regulation; Ventricular Function, Left; Ventricular Remodeling

IGF-1 plays an important role in cardiovascular homeostasis, and plasma levels of IGF-1 correlate inversely with systolic function in heart failure. It is not known to what extent circulating IGF-1 secreted by the liver and local autocrine/paracrine IGF-1 expressed in the myocardium contribute to these beneficial effects on cardiac function and morphology. In the present study, we used a mouse model of liver-specific inducible deletion of the IGF-1 gene (LI-IGF-1 -/- mouse) in an attempt to evaluate the importance of circulating IGF-I on cardiac morphology and function under normal and pathological conditions, with an emphasis on its regulatory role in myocardial phosphocreatine metabolism. Echocardiography was performed in LI-IGF-1 -/- and control mice at rest and during dobutamine stress, both at baseline and post myocardial infarction (MI). High-energy phosphate metabolites were compared between LI-IGF-1 -/- and control mice at 4 weeks post MI. We found that LI-IGF-1 -/- mice had significantly greater left ventricular dimensions at baseline and showed a greater relative increase in cardiac dimensions, as well as deterioration of cardiac function, post MI. Myocardial creatine content was 17.9% lower in LI-IGF-1 -/- mice, whereas there was no detectable difference in high-energy nucleotides. These findings indicate an important role of circulating IGF-1 in preserving cardiac structure and function both in physiological settings and post MI.

Topics: Animals; Disease Models, Animal; Heart Ventricles; Insulin-Like Growth Factor I; Mice; Mice, Knockout; Myocardial Infarction; Myocardium; Phosphocreatine; Ultrasonography; Ventricular Remodeling

One of the most powerful damaging factors during inflammation is hyperactivation of the free-radical oxidation processes. The condition of lipid peroxidation (LPO) and antioxidant activity (AOA) systems in liver has been studied in experiment on 55 male Chinchilla rabbits with widespread purulent peritonitis (WPP) model. The development of WPP leads to expressed of free-radical oxidation processes in liver that is manifested by systemic accumulation of toxic LPO products and a decrease in the activity of antioxidants. Comparative study of the influence of metabolic drugs citoflavin and neoton on the LPO and AOA systems has been conducted. It is established that citoflavin (containing succinic acid) exhibits more pronounced antioxidant properties, provides effective and fast restoration of the balance of LPO and AOA processes, and increases the speed of elimination of free radical.

Topics: Animals; Antioxidants; Cardiotonic Agents; Disease Models, Animal; Drug Combinations; Flavin Mononucleotide; Free Radicals; Inosine Diphosphate; Lipid Peroxidation; Liver; Male; Niacinamide; Peritonitis; Phosphocreatine; Rabbits; Succinates

The influence of creatine or its derivates on the cell energy potential may be one of the possibl approaches to induce neuroprotection. Effect of creamide (creatinylglycine ethylic ether fumarate) on the brain injury was studied in the experimental model of the brain ischemia/reperfusion in rats. The experiments were carried out in 14-20 weeks old male Wistar rats weighing 240-300 g, anesthetized by chloral hydrate (430 mg/kg). Creamide was administered intravenously at the doses of 50, 70, 140, and 280 mg/kg. For comparison phosphocreatine was used at the dose of 255 mg/kg. Creamide and phosphocreatine were administered intravenously (in volume of 1 ml within 5 min) 30 min before cerebral middle artery occlusion. Focal cerebral ischemia for 30 min was produced by endovascular suture occlusion with the subsequent 48 h reperfusion period. Creamide administration resulted in dose-dependent decrease of brain ischemic injury. Creamide administered at the doses of 140 and 280 mg/kg was more effective as compared with phosphocreatine (255 mg/kg). The data obtained open new perspectives for further research and development of new creatine-derived drugs with neuroprotective action.

Topics: Animals; Brain; Brain Ischemia; Disease Models, Animal; Dose-Response Relationship, Drug; Infarction, Middle Cerebral Artery; Injections, Intravenous; Male; Neuroprotective Agents; Phosphocreatine; Rats; Rats, Wistar; Reperfusion Injury; Time Factors

Huntington's disease (HD) is associated with impaired energy metabolism in the brain. Creatine kinase (CK) catalyzes ATP-dependent phosphorylation of creatine (Cr) into phosphocreatine (PCr), thereby serving as readily available high-capacity spatial and temporal ATP buffering.. Substantial evidence supports a specific role of the Cr/PCr system in neurodegenerative diseases. In the brain, the Cr/PCr ATP-buffering system is established by a concerted operation of the brain-specific cytosolic enzyme BB-CK and ubiquitous mitochondrial uMt-CK. It is not yet established whether the activity of these CK isoenzymes is impaired in HD.. We measured PCr, Cr, ATP and ADP in brain extracts of 3 mouse models of HD - R6/2 mice, N171-82Q and HdhQ(111) mice - and the activity of CK in cytosolic and mitochondrial brain fractions from the same mice.. The PCr was significantly increased in mouse HD brain extracts as compared to nontransgenic littermates. We also found an approximately 27% decrease in CK activity in both cytosolic and mitochondrial fractions of R6/2 and N171-82Q mice, and an approximately 25% decrease in the mitochondria from HdhQ(111) mice. Moreover, uMt-CK and BB-CK activities were approximately 63% lower in HD human brain samples as compared to nondiseased controls.. Our findings lend strong support to the role of impaired energy metabolism in HD, and point out the potential importance of impairment of the CK-catalyzed ATP-buffering system in the etiology of HD.

Topics: Animals; Brain; Brain Chemistry; Chromatography, High Pressure Liquid; Creatine Kinase, BB Form; Disease Models, Animal; Huntington Disease; Mice; Mice, Transgenic; Mitochondria; Phosphocreatine

To evaluate whether dynamic alterations in high-energy phosphate (HEP) occur in postischemic "stunned" myocardium (SM) in canine model and to investigate the correlation between HEP and cardiac function, using cine magnetic resonance imaging (cine-MRI) and phosphorus-31 magnetic resonance spectroscopy (31P-MRS).. Dogs (n = 13) underwent cine MRI and 31P-MRS at 60 minutes, 8 days after 10 minutes full left anterior descending occlusion followed by reperfusion. The same MRI/MRS experiments were repeated on 5 reference animals (dogs without ischemic reperfusion) at the same time points to serve as internal reference myocardium (RM). After MR data acquisitions, the SM dogs (n = 3 at 60 minutes; n = 10 at 60 minutes and day 8) and RM dogs (n = 5) were euthanized and myocardial tissues were sampled for histologic study by triphenyltetrazolium chloride staining, hematoxylin and eosin staining, and electron microscopic examination.. The myocardial stunning at 60 minutes was confirmed by electron microscopy examinations from the 3 randomly chosen animals with SM. The phosphocreatine (PCr)/β- adenosine triphosphate (ATP) ratio of SM was significantly lower at 60 minutes than that at day 8 (1.07 ± 0.20 vs. 1.97 ± 0.28, P < 0.05). However, no significant difference was found between 60 minutes and day 8 in RM group (1.91 ± 0.14 at 60 minutes vs. 1.89 ± 0.16 at day 8, P > 0.05). At 60 minutes, the PCr/β-ATP ratio has significant difference between SM and RM groups; while at day 8, the ratio shows no significant difference between the 2 groups. The same results were obtained for left ventricle ejection fraction (LVEF). In SM group, LVEF has good correlation with myocardial PCr/β-ATP ratios at 60 minutes (R2 = 0.71, P < 0.05) and at day 8 (R2 = 0.73, P < 0.05), respectively.. The HEP alterations were confirmed by 31P-MRS in SM and there is a good correlation between PCr/β-ATP ratio and LVEF for SM at 60 minutes and recovered myocardium at day 8. The combined MRS/MRI method offers the potential to systematically assess the cardiac function, morphology, and metabolism of SM. These MRS/MRI biomarker datasets could be used to dynamically monitor therapeutic efficiency and predict cardiac events.

Topics: Adenosine Triphosphate; Animals; Biomarkers; Cardiotonic Agents; Disease Models, Animal; Dogs; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Myocardial Stunning; Phosphocreatine

We determined the metabolic changes that precede cell death in the dystrophic proline-23-histidine (P23H) line 3 (P23H-3) rat retina compared with the normal Sprague-Dawley (SD) rat retina. Metabolite levels and metabolic enzymes were analyzed early in development and during the early stages of degeneration in the P23H-3 retina. Control and degenerating retinas showed an age-dependent change in metabolite levels and enzymatic activity, particularly around the time when phototransduction was activated. However, lactate dehydrogenase (LDH) activity was significantly higher in P23H-3 than SD retina before the onset of photoreceptor death. The creatine/phosphocreatine system did not contribute to the increase in ATP, because phosphocreatine levels, creatine kinase, and expression of the creatine transporter remained constant. However, Na(+)-K(+)-ATPase and Mg(2+)-Ca(2+)-ATPase activities were increased in the developing P23H-3 retina. Therefore, photoreceptor apoptosis in the P23H-3 retina occurs in an environment of increased LDH, ATPase activity, and higher-than-normal ATP levels. We tested the effect of metabolic challenge to the retina by inhibiting monocarboxylate transport with alpha-cyano-4-hydroxycinnamic acid or systemically administering the phosphodiesterase inhibitor sildenafil. Secondary to monocarboxylate transport inhibition, the P23H-3 retina did not demonstrate alterations in metabolic activity. However, administration of sildenafil significantly reduced LDH activity in the P23H-3 retina and increased the number of terminal deoxynucleotidyl transferase biotin-dUPT nick end-labeled photoreceptor cells. Photoreceptor cells with a rhodopsin mutation display an increase in apoptotic markers secondary to inhibition of a phototransduction enzyme (phosphodiesterase), suggesting increased susceptibility to altered cation entry.

Topics: Adenosine Triphosphate; Age Factors; Animals; Apoptosis; Ca(2+) Mg(2+)-ATPase; Coumaric Acids; Creatine; Creatine Kinase; Disease Models, Animal; Disease Progression; Energy Metabolism; Histidine; L-Lactate Dehydrogenase; Membrane Transport Proteins; Monocarboxylic Acid Transporters; Mutation; Phosphocreatine; Phosphodiesterase Inhibitors; Piperazines; Proline; Purines; Rats; Rats, Sprague-Dawley; Rats, Transgenic; Retina; Retinitis Pigmentosa; Sensory Rhodopsins; Sildenafil Citrate; Sodium-Potassium-Exchanging ATPase; Sulfones

Adriamycin (ADR) is an established, life-saving antineoplastic agent, the use of which is often limited by cardiotoxicity. ADR-induced cardiomyopathy is often accompanied by depressed myocardial high-energy phosphate (HEP) metabolism. Impaired HEP metabolism has been suggested as a potential mechanism of ADR cardiomyopathy, in which case the bioenergetic decline should precede left ventricular (LV) dysfunction. We tested the hypothesis that murine cardiac energetics decrease before LV dysfunction following ADR (5 mg/kg ip, weekly, 5 injections) in the mouse. As a result, the mean myocardial phosphocreatine-to-ATP ratio (PCr/ATP) by spatially localized (31)P magnetic resonance spectroscopy decreased at 6 wk after first ADR injection (1.79 + or - 0.18 vs. 1.39 + or - 0.30, means + or - SD, control vs. ADR, respectively, P < 0.05) when indices of systolic and diastolic function by magnetic resonance imaging were unchanged from control values. At 8 wk, lower PCr/ATP was accompanied by a reduction in ejection fraction (67.3 + or - 3.9 vs. 55.9 + or - 4.2%, control vs. ADR, respectively, P < 0.002) and peak filling rate (0.56 + or - 0.12 vs. 0.30 + or - 0.13 microl/ms, control vs. ADR, respectively, P < 0.01). PCr/ATP correlated with peak filling rate and ejection fraction, suggesting a relationship between cardiac energetics and both LV systolic and diastolic dysfunction. In conclusion, myocardial in vivo HEP metabolism is impaired following ADR administration, occurring before systolic or diastolic abnormalities and in proportion to the extent of eventual contractile abnormalities. These observations are consistent with the hypothesis that impaired HEP metabolism contributes to ADR-induced myocardial dysfunction.

Topics: Adenosine Triphosphate; Animals; Antibiotics, Antineoplastic; Disease Models, Animal; Down-Regulation; Doxorubicin; Energy Metabolism; Magnetic Resonance Imaging, Cine; Magnetic Resonance Spectroscopy; Male; Mice; Mice, Inbred C57BL; Myocardial Contraction; Myocardium; Phosphocreatine; Stroke Volume; Time Factors; Ventricular Dysfunction, Left; Ventricular Function, Left

The forced swim test (FST) is a behavioral paradigm that is predicative of antidepressant activity in rodents. The objective of this study was to examine the effects of desipramine (DMI) pretreatment on behavioral and regional neurochemical responses in the left dorsolateral prefrontal cortex (DLPFC) and hippocampus of mice exposed to the FST using proton magnetic resonance spectroscopy ((1)H-MRS). An ultra short echo stimulated echo acquisition (STEAM) localization sequence (TR/TM/TE=5000/20/2.2ms) was used to measure in vivo proton spectra from the left DLPFC (voxel volume: 7microl) and hippocampus (6microl) of C57BL/6 mice at 9.4T and acquired proton spectra post-processed offline with LCModel. The FST induced significant increase of glutamate (Glu) and myo-inositol (mIns) concentrations in the left DLPFC and hippocampus, respectively. In addition, creatine+phosphocreatine (Cr+PCr) concentrations in the left DLPFC were significantly decreased as compared to control. The metabolic alterations induced by the FST were reverted to level similar to control by acute DMI administration. Our results suggest that glutamatergic activity and glial cell dysfunction may contribute to the pathophysiological mechanisms underlying depression and that modulation of synaptic neurotransmitter concentrations represents a potential target for antidepressant drug development.

Topics: Animals; Behavior, Animal; Brain Chemistry; Choline; Creatine; Desipramine; Disease Models, Animal; Enzyme Inhibitors; Glutamine; Hippocampus; Inositol; Magnetic Resonance Spectroscopy; Male; Mass Spectrometry; Mice; Mice, Inbred C57BL; Phosphocreatine; Prefrontal Cortex; Protons; Stress, Psychological; Swimming

Bioenergetic homeostasis is altered in heart failure and may play an important role in pathogenesis. p53 has been implicated in heart failure, and although its role in regulating tumorigenesis is well characterized, its activities on cellular metabolism are just beginning to be understood. We investigated the role of p53 and its transcriptional target gene TP53-induced glycolysis and apoptosis regulator (TIGAR) in myocardial energy metabolism under conditions simulating ischemia that can lead to heart failure. Expression of p53 and TIGAR was markedly upregulated after myocardial infarction, and apoptotic myocytes were decreased by 42% in p53-deficient mouse hearts compared with those in wild-type mice. To examine the effect of p53 on energy metabolism, cardiac myocytes were exposed to hypoxia. Hypoxia induced p53 and TIGAR expression in a p53-dependent manner. Knockdown of p53 or TIGAR increased glycolysis with elevated fructose-2,6-bisphosphate levels and reduced myocyte apoptosis. Hypoxic stress decreased phosphocreatine content and the mitochondrial membrane potential of myocytes without changes in ATP content, the effects of which were prevented by the knockdown of TIGAR. Inhibition of glycolysis by 2-deoxyglucose blocked these bioenergetic effects and TIGAR siRNA-mediated prevention of apoptosis, and, in contrast, overexpression of TIGAR reduced glucose utilization and increased apoptosis. Our data demonstrate that p53 and TIGAR inhibit glycolysis in hypoxic myocytes and that inhibition of glycolysis is closely involved in apoptosis, suggesting that p53 and TIGAR are significant mediators of cellular energy homeostasis and cell death under ischemic stress.

Topics: Adenosine Triphosphate; Animals; Apoptosis; Apoptosis Regulatory Proteins; Cell Hypoxia; Cells, Cultured; Deoxyglucose; Disease Models, Animal; Energy Metabolism; Glycolysis; Homeostasis; Membrane Potential, Mitochondrial; Mice; Mice, Knockout; Myocardial Infarction; Myocytes, Cardiac; Phosphocreatine; Phosphofructokinase-2; Phosphoric Monoester Hydrolases; Proteins; Rats; RNA Interference; Stress, Physiological; Time Factors; Transfection; Tumor Suppressor Protein p53

L-DOPA-induced dyskinesia (LID) is among the motor complications that arise in Parkinson patients after a prolonged treatment with levodopa (L-DOPA). Since previous transcriptome and proteomic studies performed in the rat model of LID suggested important changes in striatal energy-related components, we hypothesize that oral creatine supplementation could prevent or attenuate the occurrence of LID. In this study, 6-hydroxydopamine-lesioned rats received a 2% creatine-supplemented diet for 1 month prior to L-DOPA therapy. During the 21 days of L-DOPA treatment, significant reductions in abnormal involuntary movements (AIMs) have been observed in the creatine-supplemented group, without any worsening of parkinsonism. In situ hybridization histochemistry and immunohistochemistry analysis of the striatum also showed a reduction in the levels of prodynorphin mRNA and FosB/DeltaFosB-immunopositive cells in creatine-supplemented diet group, an effect that was dependant on the development of AIMs. Further investigation of the bioenergetics' status of the denervated striatum revealed significant changes in the levels of creatine both after L-DOPA alone and with the supplemented diet. In conclusion, we demonstrated that combining L-DOPA therapy with a diet enriched in creatine could attenuate LID, which may represent a new way to control the motor complications associated with L-DOPA therapy.

Topics: Administration, Oral; Analysis of Variance; Animals; Creatine; Dietary Supplements; Disease Models, Animal; Dyskinesia, Drug-Induced; Energy Metabolism; Enkephalins; Female; In Vitro Techniques; Levodopa; Neostriatum; Neuroprotective Agents; Oxidopamine; Parkinsonian Disorders; Phosphocreatine; Protein Precursors; Proto-Oncogene Proteins c-fos; Rats; Rats, Sprague-Dawley; RNA, Messenger; Statistics, Nonparametric

Indirect data suggest that delayed recovery of intracellular pH (pHi) during reperfusion is involved in postconditioning protection, and calpain activity has been shown to be pH-dependent. We sought to characterize the effect of ischaemic postconditioning on pHi recovery during reperfusion and on calpain-dependent proteolysis, an important mechanism of myocardial reperfusion injury.. Isolated Sprague-Dawley rat hearts were submitted to 40 min of ischaemia and different reperfusion protocols of postconditioning and acidosis. pHi was monitored by (31)P-NMR spectroscopy. Myocardial cell death was determined by lactate dehydrogenase (LDH) and triphenyltetrazolium staining, and calpain activity by western blot measurement of alpha-fodrin degradation. In control hearts, pHi recovered within 1.5 +/- 0.24 min of reperfusion. Postconditioning with 6 cycles of 10 s ischaemia-reperfusion delayed pHi recovery slightly to 2.5 +/- 0.2 min and failed to prevent calpain-mediated alpha-fodrin degradation or to elicit protection. Lowering perfusion flow to 50% during reperfusion cycles or shortening the cycles (12 cycles of 5 s ischemia-reperfusion) resulted in a further delay in pHi recovery (4.1 +/- 0.2 and 3.5 +/- 0.3 min, respectively), attenuated alpha-fodrin proteolysis, improved functional recovery, and reduced LDH release (47 and 38%, respectively, P < 0.001) and infarct size (36 and 32%, respectively, P < 0.001). This cardioprotection was identical to that produced by lowering the pH of the perfusion buffer to 6.4 during the first 2 min of reperfusion or by calpain inhibition with MDL-28170.. These results provide direct evidence that postconditioning protection depends on prolongation of intracellular acidosis during reperfusion and indicate that inhibited calpain activity could contribute to this protection.

Topics: Acidosis; Animals; Apoptosis; Calpain; Carrier Proteins; Disease Models, Animal; Hydrogen-Ion Concentration; L-Lactate Dehydrogenase; Male; Microfilament Proteins; Myocardial Reperfusion Injury; Phosphocreatine; Rats; Rats, Sprague-Dawley

Near-infrared spectroscopy (NIRS) offers the ability to assess brain function at the bedside of critically ill neonates. Our group previously demonstrated a persistent reduction in the cerebral metabolic rate of oxygen (CMRO(2)) after hypoxia-ischemia (HI) in newborn piglets. The purpose of this current study was to determine the causes of this reduction by combining NIRS with magnetic resonance spectroscopy (MRS) to measure high-energy metabolites and diffusion-weighted imaging to measure cellular edema. Nine piglets were exposed to 30 min of HI and nine piglets served as controls. Proton and phosphorous MRS spectra, apparent diffusion coefficient (ADC) maps, and CMRO(2) measurements were collected periodically before and for 5.5 h after HI. A significant decrease in CMRO(2) (26 +/- 7%) was observed after HI. Incomplete recovery of nucleotide triphosphate concentration (8 +/- 3%

Topics: Animals; Animals, Newborn; Brain; Brain Edema; Diffusion Magnetic Resonance Imaging; Disease Models, Animal; Energy Metabolism; Hypoxia-Ischemia, Brain; Lactic Acid; Magnetic Resonance Spectroscopy; Mitochondria; Oxygen Consumption; Phosphates; Phosphocreatine; Recovery of Function; Spectroscopy, Near-Infrared; Swine; Time Factors

Hypertrophic cardiomyopathy (HCM) is associated with cardiac hypertrophy, diastolic dysfunction, and sudden death. Recently, it has been suggested that inefficient energy utilization could be a common molecular pathway of HCM-related mutations. We have previously generated transgenic Sprague-Dawley rats overexpressing a truncated cardiac troponin T (DEL-TNT) molecule, displaying typical features of HCM such as diastolic dysfunction and an increased susceptibility to ventricular arrhythmias. We now studied these rats using 31P magnetic resonance spectroscopy (MRS). MRS demonstrated that cardiac energy metabolism was markedly impaired, as indicated by a decreased phosphocreatine to ATP ratio (-31%, p < 0.05). In addition, we assessed contractility of isolated cardiomyocytes. While DEL-TNT and control cardiomyocytes showed no difference under baseline conditions, DEL-TNT cardiomyocytes selectively exhibited a decrease in fractional shortening by 28% after 1 h in glucose-deprived medium (p < 0.05). Moreover, significant decreases in contraction velocity and relaxation velocity were observed. To identify the underlying molecular pathways, we performed transcriptional profiling using real-time PCR. DEL-TNT hearts exhibited induction of several genes critical for cardiac energy supply, including CD36, CPT-1/-2, and PGC-1alpha. Finally, DEL-TNT rats and controls were studied by radiotelemetry after being stressed by isoproterenol, revealing a significantly increased frequency of arrhythmias in transgenic animals. In summary, we demonstrate profound energetic alterations in DEL-TNT hearts, supporting the notion that inefficient cellular ATP utilization contributes to the pathogenesis of HCM.

Topics: Adenosine Triphosphate; Animals; Arrhythmias, Cardiac; Cardiomyopathy, Hypertrophic; Cell Size; Cells, Cultured; Disease Models, Animal; Energy Metabolism; Gene Expression Profiling; Genetic Predisposition to Disease; Humans; Magnetic Resonance Imaging; Microscopy, Electron; Mitochondria, Heart; Muscle Contraction; Mutation; Myocardium; Myocytes, Cardiac; Phosphocreatine; Rats; Rats, Sprague-Dawley; Rats, Transgenic; Reverse Transcriptase Polymerase Chain Reaction; Troponin T

Phosphocreatine-Mg-complex acetate (PCr-Mg-CPLX) is a creatine-derived compound that in previous in vitro research was able to increase neuronal creatine independently of the creatine transporter, thus providing hope to cure the hereditary syndrome of creatine transporter deficiency. In previous research we showed that it reproduces in vitro the known neuroprotective effect of creatine against anoxic damage. In the present paper we investigated if PCr-Mg-CPLX reproduces this neuroprotective effect in vivo, too. We used a mouse model of transient middle cerebral artery occlusion. Mice received PCr-Mg-CPLX or a mixture of the two separate compounds phosphocreatine (PCr) and MgSO(4), or vehicle. The injections were done 60 min and 30 min before ischemia. Forty-eight hours after ischemia neurological damage was evaluated with Clark's behavioural tests, then the infarct volume was measured. PCr-Mg-CPLX reduced the infarct volume by 48%, an effect that was not duplicated by the separate administration of PCr and MgSO(4) and the neurological damage was decreased in a statistically significant way. We conclude that PCr-Mg-CPLX affords in vivo neuroprotection when administered before ischemia. These results are comparable to previous research on creatine administration in experimental stroke. PCr-Mg-CPLX maintains creatine-like neuroprotective effects in vivo as well as in vitro. Our study suggests that PCr-Mg-CPLX might have a therapeutic role in the treatment of hereditary creatine transporter deficiency and of conditions where there is a high risk of impending stroke or cerebral ischemic damage, like high-risk transient ischemic attacks, open heart surgery, and carotid surgery.

Topics: Animals; Brain Infarction; Brain Ischemia; Creatine; Cytoprotection; Disease Models, Animal; Infarction, Middle Cerebral Artery; Magnesium; Male; Membrane Transport Proteins; Mice; Nerve Degeneration; Neuroprotective Agents; Phosphocreatine; Treatment Outcome

A course of adenocine (cardiotonic drug with a pronounced cardioprotective effect) for severe experimental heart failure caused by toxic allergic myocarditis (for 10 days) more effectively restored the systolic and diastolic function of the heart and arrested systemic inflammatory response syndrome than traditional therapy with angiotensin-converting enzyme inhibitors, beta-adrenoblockers, or diuretics in combination with neoton. Adenocine is characterized by a synergistic effect, and none of its ingredients alone (nicotinamide adenine dinucleotide, inosine, beta-acetyldigoxin, oxyfedrine) exhibits similar effect.

Topics: Adrenergic beta-Antagonists; Angiotensin-Converting Enzyme Inhibitors; Animals; Cardiotonic Agents; Disease Models, Animal; Diuretics; Endotoxemia; Heart Failure; Myocarditis; Phosphocreatine; Rabbits; Systemic Inflammatory Response Syndrome; Treatment Outcome

The p38 MAP kinases are stress-activated MAP kinases whose induction is often associated with the onset of heart failure. This study investigated the role of p38 MAP kinase isoforms in the regulation of myocardial contractility and ischemia/reperfusion injury using mice with cardiac-specific expression of kinase dead (dominant negative) mutants of p38alpha (p38alphadn) or p38beta (p38betadn). Hearts were subjected to 20 min ischemia and 40 min reperfusion. Immunofluorescence staining for p38alphadn and p38betadn protein was performed on neonatal cardiomyocytes infected with adenovirus expressing flag-tagged p38alphadn and p38betadn protein. Basal contractile function was increased in both p38alphadn and p38betadn hearts compared to WT. Ischemic injury was increased in p38betadn vs. WT hearts, as indicated by lower posti-schemic recoveries of contractile function and ATP. However, despite a similar increase in contractility, ischemic injury was not increased in p38alphadn vs. WT hearts. Immunohistological analysis of cardiomyocytes with comparable levels of protein overexpression show that p38alphadn and p38betadn proteins were co-localized with sarcomeric alpha-actinin, however, p38alphadn was detected in the nucleus while p38betadn was exclusively detected in the cytosol. In summary, attenuated p38 activity led to increased myocardial contractility; specific isoforms of p38 and their sub-cellular localization may have different roles in modulating ischemic injury.

Topics: Adenosine Triphosphate; Animals; Animals, Newborn; Cell Nucleus; Cells, Cultured; Cytosol; Disease Models, Animal; Humans; Hydrogen-Ion Concentration; Isoenzymes; Mice; Mice, Transgenic; Mitogen-Activated Protein Kinase 11; Mitogen-Activated Protein Kinase 14; Mutation; Myocardial Contraction; Myocardial Reperfusion Injury; Myocardium; Myosin Heavy Chains; Phosphocreatine; Promoter Regions, Genetic; Rats; Rats, Sprague-Dawley; Recovery of Function; Time Factors; Transfection; Ventricular Myosins

To examine whether nutritional supplementation with SkQ1 can reduce myocardial ischemia-reperfusion injury in vivo, Wistar rats were fed a regular diet supplemented with different doses of SkQ1 for two or three weeks. Control groups of rats were fed the same diet supplemented with NaBr. Anaesthetized rats were subjected to 40-min regional myocardial ischemia and 1-h reperfusion. Myocardial infarct size was measured by 2,3,5-triphenyl tetrazolium chloride (TTC) staining method. SkQ1-fed rats (125 nmol/kg/day for two weeks and 250 nmol/kg/day for two and three weeks) revealed significantly smaller myocardial infarction and less lactate dehydrogenase (LDH) and creatine kinase-MB fraction (CK-MB) activity elevations in plasma at the end of reperfusion compared with the controls. This effect was combined with improvement of energy state of the area at risk at the end of reperfusion, namely, augmentation of adenine nucleotide content, two-fold increase in phosphocreatine, reduction of lactate accumulation and decrease of lactate/pyruvate ratio in myocardial tissue. Therefore, nutritional supplementation with SkQ1 renders the hearts resistant to ischemia-reperfusion injury affecting oxidative metabolism of postischemic cardiomyocytes.

Topics: Animals; Creatine Kinase, MB Form; Dietary Supplements; Disease Models, Animal; Heart; Humans; L-Lactate Dehydrogenase; Myocardial Reperfusion Injury; Myocardium; Oxidative Stress; Phosphocreatine; Plastoquinone; Rats; Rats, Wistar

Phosphorus magnetic resonance spectroscopy ((31)P MRS) often reveals apparently normal brain metabolism in the first hours after intrapartum hypoxia-ischemia (HI) at a time when conventional clinical assessment of injury severity is problematic. We aimed to elucidate very-early, injury-severity biomarkers. Twenty-seven newborn piglets underwent cerebral HI: (31)P-MRS measures approximately 2 h after HI were compared between injury groups defined by secondary-energy-failure severity as quantified by the minimum nucleotide triphosphate (NTP) observed after 6 h. For severe and moderate injury versus baseline, [Pi]/[total exchangeable high-energy phosphate pool (EPP)] was increased (p < 0.001 and < 0.02, respectively), and [NTP]/[EPP] decreased (p < 0.03 and < 0.006, respectively): severe-injury [Pi]/[EPP] was also increased versus mild injury (p < 0.04). Mild-injury [phosphocreatine]/[EPP] was increased (p < 0.004). Severe-injury intracellular pH was alkaline versus baseline (p < 0.002). For severe and moderate injury [total Mg]/[ATP] (p < 0.0002 and < 0.02, respectively) and [free Mg] (p < 0.0001 and < 0.02, respectively) were increased versus baseline. [Pi]/[EPP], [phosphocreatine]/[Pi] and [NTP]/[EPP] correlated linearly with injury severity (p < 0.005, < 0.005 and < 0.02, respectively). Increased [Pi]/[EPP], intracellular pH and intracellular Mg approximately 2 h after intrapartum HI may prognosticate severe injury, whereas increased [phosphocreatine]/[EPP] may suggest mild damage. In vivo(31)P MRS may have potential to provide very-early prognosis in neonatal encephalopathy.

Topics: Adenosine Triphosphate; Animals; Animals, Newborn; Disease Models, Animal; Female; Hypoxia-Ischemia, Brain; Magnetic Resonance Spectroscopy; Male; Phosphocreatine; Phosphorus; Spectrum Analysis; Swine; Time Factors

Modular control analysis (MoCA; Diolez P, Deschodt-Arsac V, Raffard G, Simon C, Santos PD, Thiaudiere E, Arsac L, Franconi JM. Am J Physiol Regul Integr Comp Physiol 293: R13-R19, 2007) was applied here on perfused hearts to describe the modifications of the regulation of heart energetics induced in mice exposed to 3-wk chronic hypoxia. MoCA combines 31P-NMR spectroscopy and modular (top down) control analysis to describe the integrative regulation of energy metabolism in the intact beating heart, on the basis of two modules [ATP/phosphocreatine (PCr) production and ATP/PCr consumption] connected by the energetic intermediates. In contrast with previous results in rat heart, in which all control of contraction was on ATP demand, mouse heart energetics presented a shared control of contraction between ATP/PCr-producing and -consuming modules. In chronic hypoxic mice, the decrease in heart contractile activity and PCr-to-ATP ratio was surprisingly associated with an important and significant higher response of ATP/PCr production (elasticity) to PCr changes compared with control hearts (-10.4 vs. -2.46). By contrast, no changes were observed in ATP/PCr consumption since comparable elasticities were observed. Since elasticities determine the regulation of energetics of heart contraction, the present results show that this new parameter may be used to uncover the origin of the observed dysfunctions under chronic hypoxia conditions. Considering the decrease in mitochondrial content reported after exposure to chronic hypoxia, it appears that the improvement of ATP/PCr production response to ATP demand may be viewed as a positive adaptative mechanism. It now appears crucial to understand the very processes responsible for ATP/PCr producer elasticity toward the energetic intermediates, as well as their regulation.

Topics: Adaptation, Physiological; Adenosine Triphosphate; Animals; Chronic Disease; Disease Models, Animal; Elasticity; Energy Metabolism; Female; Heart Rate; Hypoxia; Kinetics; Magnetic Resonance Spectroscopy; Mice; Mitochondria, Heart; Myocardial Contraction; Myocardium; Phosphocreatine; Systems Biology; Ventricular Pressure

Adenoviral gene transfer of sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA)2a to the hypertrophic heart in vivo has been consistently reported to lead to enhanced myocardial contractility. It is unknown if the faster skeletal muscle isoform, SERCA1, expressed in the whole heart in early failure, leads to similar improvements and whether metabolic requirements are maintained during an adrenergic challenge. In this study, Ad.cmv.SERCA1 was delivered in vivo to aortic banded and sham-operated Sprague-Dawley rat hearts. The total SERCA content increased 34%. At 48-72 h posttransfer, echocardiograms were acquired, hearts were excised and retrograded perfused, and hemodynamics were measured parallel to NMR measures of the phosphocreatine (PCr)-to-ATP ratio (PCr/ATP) and energy substrate selection at basal and high workloads (isoproterenol). In the Langendorff mode, the rate-pressure product was enhanced 27% with SERCA1 in hypertrophic hearts and 10% in shams. The adrenergic response to isoproterenol was significantly potentiated in both groups with SERCA1. 31P NMR analysis of PCr/ATP revealed that the ratio remained low in the hypertrophic group with SERCA1 overexpression and was not further compromised with adrenergic challenge. 13C NMR analysis revealed fat and carbohydrate oxidation were unaffected at basal with SERCA1 expression; however, there was a shift from fats to carbohydrates at higher workloads with SERCA1 in both groups. Transport of NADH-reducing equivalents into the mitochondria via the alpha-ketoglutamate-malate transporter was not affected by either SERCA1 overexpression or adrenergic challenge in both groups. Echocardiograms revealed an important distinction between in vivo versus ex vivo data. In contrast to previous SERCA2a studies, the echocardiogram data revealed that SERCA1 expression compromised function (fractional shortening) in the hypertrophic group. Shams were unaffected. While our ex vivo findings support much of the earlier cardiomyocyte and transgenic data, the in vivo data challenge previous reports of improved cardiac function in heart failure models after SERCA intervention.

Topics: Adenosine Triphosphate; Adenoviridae; Adrenergic beta-Agonists; Animals; Calcium-Binding Proteins; Calsequestrin; Cardiomegaly; Carrier Proteins; Citric Acid Cycle; Disease Models, Animal; Energy Metabolism; Gene Transfer Techniques; Genetic Therapy; Genetic Vectors; Hemodynamics; Isoproterenol; Magnetic Resonance Spectroscopy; Male; Mitochondria, Heart; Muscle, Skeletal; Myocardial Contraction; Myocardium; Oxidation-Reduction; Palmitic Acid; Phosphocreatine; Rats; Rats, Sprague-Dawley; Sarcoplasmic Reticulum Calcium-Transporting ATPases; Time Factors; Ultrasonography

Neuroprotective therapeutics stop or slow down the degeneration process in animal models of Parkinson's disease (PD). Neuronal survival in PD animal models is often measured by immunohistochemistry. However, dynamic changes in the pathology of the brain cannot be explored with this technique. Application of proton magnetic resonance (MR) imaging (MRI) and spectroscopy (MRS) can cover this lacuna as these techniques are non-invasive and can be repeated over time in the same animal. Therefore, the sensitivity of both techniques to measure changes in PD-pathology was explored in an experiment studying the neuroprotective effects of the vigilance enhancer modafinil in a marmoset PD model. Eleven marmoset monkeys were treated with the neurotoxin 1-methyl-1,2,3,6-tetrahydropyridine (MPTP). Six of these 11 animals, simultaneously, received a daily oral dose of modafinil (100 mg/kg) and five received vehicle for 27 days. MR experiments were performed at baseline and 1 and 3.5 weeks after the MPTP intoxication period after which brains were analyzed with immunohistochemistry. Tyrosine hydroxylase immunoreactive (TH-IR) staining of dopamine neurons of the substantia nigra pars compacta confirmed that modafinil was able to partially prevent the MPTP-induced neuronal damage. In MRS, N-acetylaspartate (NAA)/phosphocreatine (tCR) ratios confirmed the protective effect indicating that this is a sensitive measure to detect neuroprotection in the MPTP marmoset model. Furthermore, the number of TH-IR positive neurons and the NAA/tCR ratio were significantly correlated to behavioral observations indicating that the changes measured in the brain are also reflected in the behavior and vice versa.

Topics: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; Animals; Aspartic Acid; Benzhydryl Compounds; Biomarkers; Brain; Callithrix; Disease Models, Animal; Dopamine; Drug Administration Schedule; Immunohistochemistry; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Modafinil; Nerve Degeneration; Neurons; Neuroprotective Agents; Neurotoxins; Parkinsonian Disorders; Phosphocreatine; Predictive Value of Tests; Reproducibility of Results; Substantia Nigra; Treatment Outcome; Tyrosine 3-Monooxygenase

Mitochondrial activity is altered in skeletal muscle of obese, insulin-resistant or type 2 diabetic patients. We hypothesized that this situation was associated with profound adaptations in resting muscle energetics. For that purpose, we used in vivo (31)P-nuclear magnetic resonance ((31)P-NMR) in male sedentary Wistar rats fed with obesogenic diets known to induce alterations in muscle mitochondrial activity.. Two experimental diets (high sucrose and high fat) were provided for 6 weeks at two levels of energy (standard, N and high, H) and compared to control diet. The rates of the adenosine triphosphate (ATP) exchange between phosphocreatine (PCr) and gamma-ATP (k(a)) and beta-adenosine diphosphate (beta-ADP) to beta-ATP (k(b)) were evaluated using (31)P-NMR in resting gastrocnemius muscle. Muscle contents in phosphorylated compounds as well as creatine, were assessed using (31)P-NMR and biochemical assays, respectively.. ATP content increased by 6.7-8.5% in standard-energy high-sucrose (NSU), high-energy high-fat (HF) and high-energy high-sucrose (HSU) groups compared to control (P < 0.05), whereas PCr content decreased by 4.2-6.4% (P < 0.01). Consequently, PCr to ATP ratio decreased in NSU, HF, and HSU groups, compared to control (P < 0.01). Furthermore in high-energy groups (HF and HSU) compared to control, creatine contents were decreased by 14-19% (P < 0.001), whereas k(a) and k(b) fluxes were increased by 89-133% (P < 0.001) and 243-277% (P < 0.01), respectively.. Our in vivo data showed adaptations of resting skeletal muscle energetics in response to high-energy diets. Increased activity of enzymes catalyzing ATP production may reflect a compensatory mechanism to face impaired mitochondrial ATP synthesis in order to preserve intracellular energy homeostasis.

Topics: Adaptation, Physiological; Adenosine Diphosphate; Adenosine Triphosphate; Animals; Dietary Fats; Dietary Sucrose; Disease Models, Animal; Energy Metabolism; Hydrogen-Ion Concentration; Kinetics; Magnetic Resonance Spectroscopy; Male; Mitochondria, Muscle; Muscle, Skeletal; Obesity; Phosphocreatine; Phosphorus Isotopes; Rats; Rats, Wistar

This study utilized porcine models of postinfarction left ventricular (LV) remodeling [myocardial infarction (MI); n = 8] and concentric LV hypertrophy secondary to aortic banding (AoB; n = 8) to examine the relationships between regional myocardial contractile function (tagged MRI), wall stress (MRI and LV pressure), and bioenergetics ((31)P-magnetic resonance spectroscopy). Physiological assessments were conducted at a 4-wk time point after MI or AoB surgery. Comparisons were made with size-matched normal animals (normal; n = 8). Both MI and AoB instigated significant LV hypertrophy. Ejection fraction was not significantly altered in the AoB group, but significantly decreased in the MI group (P < 0.01 vs. normal and AoB). Systolic and diastolic wall stresses were approximately two times greater than normal in the infarct region and border zone. Wall stress in the AoB group was not significantly different from that in normal hearts. The infarct border zone demonstrated profound bioenergetic abnormalities, especially in the subendocardium, where the ratio of PCr/ATP decreased from 1.98 +/- 0.16 (normal) to 1.06 +/- 0.30 (MI; P < 0.01). The systolic radial thickening fraction and the circumferential shortening fraction in the anterior wall were severely reduced (MI, P < 0.01 vs. normal). The radial thickening fraction and circumferential shortening fraction in the AoB group were not significantly different from normal. The severely elevated wall stress in the infarct border zone was associated with a significant increase in chemical energy demand and abnormal myocardial energy metabolism. Such severe metabolic perturbations cannot support normal cardiac function, which may explain the observed regional contractile abnormalities in the infarct border zone.

Topics: Adenosine Triphosphate; Animals; Aorta; Coronary Vessels; Disease Models, Animal; Energy Metabolism; Hypertrophy, Left Ventricular; Ligation; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Myocardial Contraction; Myocardial Infarction; Myocardium; Phosphocreatine; Research Design; Stress, Mechanical; Stroke Volume; Swine; Ventricular Pressure; Ventricular Remodeling

The heterogeneity across the left ventricular wall is characterized by higher rates of oxygen consumption, systolic thickening fraction, myocardial perfusion, and lower energetic state in the subendocardial layers (ENDO). During dobutamine stimulation-induced demand ischemia, the transmural distribution of energy demand and metabolic markers of ischemia are not known. In this study, hemodynamics, transmural high-energy phosphate (HEP), 2-deoxyglucose-6-phosphate (2-DGP) levels, and myocardial blood flow (MBF) were determined under basal conditions, during dobutamine infusion (DOB: 20 microg x kg(-1) x min(-1) iv), and during coronary stenosis + DOB + 2-deoxyglucose (2-DG) infusion. DOB increased rate pressure products (RPP) and MBF significantly without affecting the subendocardial-to-subepicardial blood flow ratio (ENDO/EPI) or HEP levels. During coronary stenosis + DOB + 2-DG infusion, RPP, ischemic zone (IZ) MBF, and ENDO/EPI decreased significantly. The IZ ratio of creatine phosphate-to-ATP decreased significantly [2.30 +/- 0.14, 2.06 +/- 0.13, and 2.04 +/- 0.11 to 1.77 +/- 0.12, 1.70 +/- 0.11, and 1.72 +/- 0.12 for EPI, midmyocardial (MID), and ENDO, respectively], and 2-DGP accumulated in all layers, as evidenced by the 2-DGP/PCr (0.55 +/- 0.12, 0.52 +/- 0.10, and 0.37 +/- 0.08 for EPI, MID, and ENDO, respectively; P < 0.05, EPI > ENDO). In the IZ the wet weight-to-dry weight ratio was significantly increased compared with the normal zone (5.9 +/- 0.5 vs. 4.4 +/- 0.4; P < 0.05). Thus, in the stenotic perfused bed, during dobutamine-induced high cardiac work state, despite higher blood flow, the subepicardial layers showed the greater metabolic changes characterized by a shift toward higher carbohydrate metabolism, suggesting that a homeostatic response to high-cardiac work state is characterized by more glucose utilization in energy metabolism.

Topics: Adenosine Triphosphate; Animals; Coronary Circulation; Coronary Stenosis; Disease Models, Animal; Dobutamine; Dogs; Endocardium; Energy Metabolism; Glucose-6-Phosphate; Glycolysis; Hemodynamics; Lactic Acid; Magnetic Resonance Spectroscopy; Myocardial Ischemia; Myocardium; Oxygen Consumption; Pericardium; Phosphocreatine

Previous studies have shown that cerebral hypoxia results in increased activity of caspase-9, a key initiator of programmed cell death, in the cytosolic fractions of the cerebral cortex of newborn piglets. The present study tests the hypothesis that hypoxia results in increased expression of procaspase-9 and procaspase-3 in neuronal nuclear, mitochondrial and cytosolic fractions of the cerebral cortex of newborn piglets. To test this hypothesis, expression of procaspase-9 and procaspase-3 was determined in 10 newborn piglets divided into two groups: normoxic (Nx, n=5) and hypoxic (Hx, n=5). The hypoxic piglets were exposed to an FiO(2) of 0.06 for 1h. Tissue hypoxia was documented by ATP and phosphocreatinine (PCr) levels. Neuronal nuclear, mitochondrial and cytosolic fractions were isolated and the expression of procaspase-9 and procaspase-3 was determined by immunoblotting using specific anti-procaspase-9 and anti-procaspase-3 antibodies. ATP levels (micromol/g brain) were 4.34+/-0.36 in the Nx and 1.43+/-0.28 in the Hx (p<0.001 vs. Nx) groups. PCr levels (micromol/g brain) were 3.75+/-0.27 in the Nx and 0.69+/-0.26 in the Hx (p<0.001 vs. Nx) group. Cytosolic procaspase-9 density (ODxmm(2)) was 88.82+/-17.55 in the Nx and 215.54+/-22.77 in the Hx (p<0.001 vs. Nx). Mitochondrial procaspase-9 density (ODxmm(2)) was 104.67+/-12.75 in the Nx and 183.44+/-16.69 in the Hx (p<0.001 vs. Nx). Nuclear procaspase-9 density (ODxmm(2)) was 135.56+/-15.36 in the Nx and 190.66+/-29.35 in the Hx (p<0.001 vs. Nx). Cytosolic procaspase-3 density (ODxmm(2)) was 23.72+/-3.71 in the Nx and 92.44+/-8.46 in the Hx (p<0.001 vs. Nx). Mitochondrial procaspase-3 density (ODxmm(2)) was 22.12+/-2.97 in the Nx and 51.22+/-10.67 in the Hx (p<0.001 vs. Nx). Nuclear procaspase-3 density (ODxmm(2)) was 53.80+/-7.18 in the Nx and 84.67+/-5.63 in the Hx (p<0.001 vs. Nx). We conclude that procaspase-9 and procaspase-3 proteins increased in all cell compartments including cytosolic, mitochondrial and nuclear during hypoxia, indicating increased expression of procaspase-9 during hypoxia. We propose that following increased expression of procaspase-9 and procaspase-3, these molecules traffic among the various cell compartments and become available for their activation resulting in increased caspase-9 and caspase-3 activity.

Topics: Adenosine Triphosphate; Animals; Animals, Newborn; Apoptosis; Caspase 3; Caspase 9; Cell Compartmentation; Cell Nucleus; Cerebral Cortex; Cytosol; Disease Models, Animal; Energy Metabolism; Enzyme Activation; Hypoxia, Brain; Mitochondria; Neurons; Phosphocreatine; Phosphorylation; Subcellular Fractions; Sus scrofa; Up-Regulation

Stroke leads to energy failure and subsequent neuronal cell loss. Creatine and phosphocreatine constitute a cellular energy buffering and transport system, and dietary creatine supplementation was shown to protect neurons in several models of neurodegeneration. Although creatine has recently been found to reduce infarct size after cerebral ischemia in mice, the mechanisms of neuroprotection remained unclear. We provide evidence for augmented cerebral blood flow (CBF) after stroke in creatine-treated mice using a magnetic resonance imaging (MRI)-based technique of CBF measurement (flow-sensitive alternating inversion recovery-MRI). Moreover, improved vasodilatory responses were detected in isolated middle cerebral arteries obtained from creatine-treated animals. After 3 weeks of dietary creatine supplementation, minor changes in brain creatine, phosphocreatine, adenosine triphosphate, adenosine diphosphate and adenosine monophosphate levels were detected, which did not reach statistical significance. However, we found a 40% reduction in infarct volume after transient focal cerebral ischemia. Our data suggest that creatine-mediated neuroprotection can occur independent of changes in the bioenergetic status of brain tissue, but may involve improved cerebrovascular function.

Topics: Adenosine Triphosphate; Animals; Brain; Brain Ischemia; Cerebrovascular Circulation; Creatine; Disease Models, Animal; Magnetic Resonance Imaging; Male; Mice; Phosphocreatine

In the heart, thermal injury activates a group of intracellular cysteine proteases known as caspases, which have been suggested to contribute to myocyte inflammation and dyshomeostasis. In this study, Sprague-Dawley rats were given either a third-degree burn over 40% total body surface area plus conventional fluid resuscitation or sham burn injury. Experimental groups included 1) sham burn given vehicle, 400 microl DMSO; 2) sham burn given Q-VD-OPh (6 mg/kg), a highly specific and stable caspase inhibitor, 24 and 1 h prior to sham burn; 3) burn given vehicle, DMSO as above; 4) burn given Q-VD-OPh (6 mg/kg) 24 and 1 h prior to burn. Twenty-four hours postburn, hearts were harvested and studied with regard to myocardial intracellular sodium concentration, intracellular pH, ATP, and phosphocreatine (23Na/31P nuclear magnetic resonance); myocardial caspase-1, -3,and -8 expression; myocyte Na+ (fluorescent indicator, sodium-binding benzofurzan isophthalate); myocyte secretion of TNF-alpha, IL-1beta, IL-6, and IL-10; and myocardial performance (Langendorff). Burn injury treated with vehicle alone produced increased myocardial expression of caspase-1, -3, and -8, myocyte Na+ loading, cytokine secretion, and myocardial contractile depression; cellular pH, ATP, and phosphocreatine were stable. Q-VD-OPh treatment in burned rats attenuated myocardial caspase expression, prevented burn-related myocardial Na+ loading, attenuated myocyte cytokine responses, and improved myocardial contraction and relaxation. The present data suggest that signaling through myocardial caspases plays a pivotal role in burn-related myocyte sodium dyshomeostasis and myocyte inflammation, perhaps contributing to burn-related contractile dysfunction.

Topics: Adenosine Triphosphate; Amino Acid Chloromethyl Ketones; Animals; Burns; Calcium; Caspase 1; Caspase 3; Caspase 8; Caspase Inhibitors; Caspases; Cysteine Proteinase Inhibitors; Disease Models, Animal; Heart Diseases; Homeostasis; Hydrogen-Ion Concentration; Interleukin-10; Interleukin-1beta; Interleukin-6; Magnetic Resonance Spectroscopy; Male; Myocardial Contraction; Myocytes, Cardiac; Phosphocreatine; Quinolines; Rats; Rats, Sprague-Dawley; Severity of Illness Index; Signal Transduction; Sodium; Tumor Necrosis Factor-alpha; Ventricular Pressure

Chronic muscle pain is a major clinical problem that is often associated with fatigue. Conversely, chronic fatigue conditions are commonly associated with muscle pain. We tested the hypothesis that muscle fatigue enhances hyperalgesia associated with injection of acidic saline into muscle. We evaluated mechanical sensitivity of the paw (von Frey) in mice after 2 intramuscular injections of saline (20 microL; pH 4, pH 5, pH 6, pH 7.2) in a fatigue and a control group. To induce fatigue, mice were run for 2 h/day for 2 days prior to the first injection and 2 h/day for 2 days prior to the second injection. Muscle lactate, pCO(2), pO(2), creatinine kinase, phosphate, and histology were examined after the fatigue task and compared to a control group. Grip force was significantly decreased after 2 h of running indicating fatigue. The fatigue task did not induce muscle damage as there was no difference in muscle lactate, pCO(2), pO(2), creatinine kinase, phosphate, or histology. The fatigue task altered the dose-response relationship to intramuscular acidic saline injections. Mechanical hyperalgesia was observed in both fatigue and control groups after intramuscular injection of pH 4.0, but only the fatigue group after injection of pH 5. Neither the fatigue nor the control group developed hyperalgesia in response to intramuscular injection of pH 6 or pH 7.2. In conclusion, fatigue modified the susceptibility of mice to acid injection of pH 5.0 to result in mechanical hyperalgesia after 2 injections of pH 5.0. The fatigue task did not produce measurable changes in the muscle tissue suggesting a central mechanism mediating the enhancement of hyperalgesia.. These data therefore show that muscle fatigue can enhance the likelihood that one develops pain to a mild insult. Clinically, this could relate to the development of pain from such conditions as repetitive strain injury, and may relate to the interrelationship between chronic pain and fatigue.

Topics: Animals; Carbon Dioxide; Cumulative Trauma Disorders; Disease Models, Animal; Dose-Response Relationship, Drug; Fatigue Syndrome, Chronic; Hyperalgesia; Hypoxia; Ischemia; Lactic Acid; Male; Mice; Mice, Inbred C57BL; Muscle Fatigue; Muscle Strength; Muscle, Skeletal; Oxygen; Pain Measurement; Phosphocreatine; Physical Stimulation; Sodium Chloride

The purpose of our study was to evaluate the postmortem interval with multi-voxel 1H-MR spectroscopy.. Twelve healthy rabbits were studied and the quantities of N-acetylaspartate, total choline, phosphocreatine and creatine were measured by 1H-MR spectroscopy after death at 0.5, 1, 2, 4, 6, 8, 12, 16, and 24 h.. The levels of Naa/Cr and Naa/Ch decreased following death, while the level of Ch/Cr increased initially and then decreased following death.. Multi-voxel proton MR spectroscopy for Naa/Cr and Ch/Cr metabolic ratio could be used in future postmortem interval studies.

Topics: Animals; Aspartic Acid; Biomarkers; Brain; Choline; Creatine; Disease Models, Animal; Embolism, Air; Female; Magnetic Resonance Spectroscopy; Male; Phosphocreatine; Postmortem Changes; Protons; Rabbits; Regression Analysis; Time Factors

The neuropathological and clinical symptoms of Huntington's disease (HD) can be simulated in animal model with systemic administration of 3-nitropropionic acid (3-NP). Energy defects in HD could be ameliorated by administration of coenzyme Q(10) (CoQ(10)), creatine, or nicotinamid. We studied the activity of creatine kinase (CK) and the function of mitochondrial respiratory chain in the brain of aged rats administered with 3-NP with and without previous application of antioxidants CoQ(10)+vitamin E. We used dynamic and steady-state methods of in vivo phosphorus magnetic resonance spectroscopy ((31)P MRS) for determination of the pseudo-first order rate constant (k(for)) of the forward CK reaction, the phosphocreatine (PCr) to adenosinetriphosphate (ATP) ratio, intracellular pH(i) and Mg(i)(2+) content in the brain. The respiratory chain function of isolated mitochondria was assessed polarographically; the concentration of CoQ(10) and alpha-tocopherol by HPLC. We found significant elevation of k(for) in brains of 3-NP rats, reflecting increased rate of CK reaction in cytosol. The function of respiratory chain in the presence of succinate was severely diminished. The activity of cytochromeoxidase and mitochondrial concentration of CoQ(10) was unaltered; tissue content of CoQ(10) was decreased in 3-NP rats. Antioxidants CoQ(10)+vitamin E prevented increase of k(for) and the decrease of CoQ(10) content in brain tissue, but were ineffective to prevent the decline of respiratory chain function. We suppose that increased activity of CK system could be compensatory to decreased mitochondrial ATP production, and CoQ(10)+vitamin E could prevent the increase of k(for) after 3-NP treatment likely by activity of CoQ(10) outside the mitochondria. Results of our experiments contributed to elucidation of mechanism of beneficial effect of CoQ(10) administration in HD and showed that the rate constant of CK is a sensitive indicator of brain energy disorder reflecting therapeutic effect of drugs that could be used as a new in vivo biomarker of neurodegenerative diseases.

Topics: Adenosine Triphosphate; Animals; Brain; Coenzymes; Creatine Kinase; Disease Models, Animal; Electron Transport Complex IV; Energy Metabolism; Huntington Disease; Hydrogen-Ion Concentration; Magnetic Resonance Spectroscopy; Male; Oxidative Phosphorylation; Phosphocreatine; Rats; Rats, Wistar; Ubiquinone; Vitamin E

Previous studies have shown that cerebral hypoxia results in increased activity of caspase-9, a key initiator of programmed cell death. We have also shown increased nitric oxide (NO) free radical generation during hypoxia in the cerebral cortex of newborn piglets. The present study tests the hypothesis that hypoxia-induced increase in caspase-9 activity in the cerebral cortex of newborn piglets is mediated by NO derived from neuronal nitric oxide synthase (nNOS). To test this hypothesis, cytosolic caspase-9 activity was determined in 15 newborn piglets divided into three groups: normoxic (Nx, n=5), hypoxic (Hx, n=5), and Hx pretreated with 7-nitroindazole sodium salt (7-NINA), a selective nNOS inhibitor, 1mg/kg, i.p., 1h prior to hypoxia (Hx+7NI, n=5). The hypoxic piglets were exposed to an FiO(2) of 0.06 for 1h. Tissue hypoxia was documented by ATP and phosphocreatinine (PCr) levels. The cytosolic fraction was obtained from the cerebral cortical tissue following centrifugation at 100,000 x g for 1h and caspase-9 activity was assayed using Ac-Leu-Glu-His-Asp-amino-4-methyl coumarin, a specific fluorogenic substrate for caspase-9. Caspase-9 activity was determined spectroflourometrically at 460 nm using 380 nm as excitation wavelength. ATP levels (micromol/g brain) were 4.35+/-0.21 in the Nx 1.43+/-0.28 in the Hx (p<0.05 versus Nx), and 1.73+/-0.33 in the Hx+7-NINA group (p<0.05 versus Nx, p=NS versus Hx). PCr levels (micromol/g brain) were 3.80+/-0.26 in the Nx, 0.96+/-0.20 in the Hx (p<0.05 versus Nx), and 1.09+/-0.39 in the Hx+7 NINA group (p<0.05 versus Nx, p=NS versus Hx). Cytosolic caspase-9 activity (nmol/mg protein/h), increased from 1.27+/-0.15 in the Nx to 2.13+/-0.14 in the Hx (p<0.05 versus Nx) compared to 1.10+/-0.21 in the Hx+7-NINA group (p<0.05 versus Hx, p=NS versus Nx). Caspase-3 activity (nmol/mg protein/h) also increased from 9.39+/-0.73 in Nx to 18.94+/-3.64 in Hx (p<0.05 versus Nx) compared to 8.04+/-1.05 in the Hx+7-NINA group (p<0.05 versus Hx, p=NS versus Nx). The data show that administration of 7-NINA, an nNOS inhibitor, prevented the hypoxia-induced increase in caspase-9 activity that leads to increase in caspase-3 activity. Since nNOS inhibition blocked the increase in caspase-9 activity during hypoxia, we conclude that hypoxia-induced increase in caspase-9 activity is mediated by nNOS derived NO. We propose that the NO generated during hypoxia leads to activation of caspase-9 and results in initiation of caspase-cascade-depend

Topics: Adenosine Triphosphate; Animals; Animals, Newborn; Apoptosis; Brain; Brain Chemistry; Caspase 9; Caspases; Cerebral Cortex; Disease Models, Animal; Enzyme Activation; Enzyme Inhibitors; Hypoxia, Brain; Indazoles; Nerve Degeneration; Nitric Oxide; Nitric Oxide Synthase Type I; Phosphocreatine; Signal Transduction; Sus scrofa; Up-Regulation

Previously, we have shown that hypoxia results in increased generation of nitric oxide free radicals in the cerebral cortex of newborn piglets that may be due to up-regulation of nitric oxide synthases, neuronal nitric oxide synthase and inducible nitric oxide synthase. The present study tests the hypothesis that hypoxia results in increased expression of neuronal nitric oxide synthase and inducible nitric oxide synthase in the cerebral cortex of newborn piglets and that the increased expression is nitric oxide-mediated. Newborn piglets, 2-4 days old, were divided to normoxic (n=4), hypoxic (n=4) and hypoxic-treated with 7-nitro-indazole-sodium salt, a selective neuronal nitric oxide synthase inhibitor (hypoxic-7-nitro-indazole-sodium salt, n=6, 1 mg/kg, 60 min prior to hypoxia). Piglets were anesthetized, ventilated and exposed to an FiO2 of 0.21 or 0.07 for 60 min. Cerebral tissue hypoxia was documented biochemically by determining ATP and phosphocreatine. The expression of neuronal nitric oxide synthase and inducible nitric oxide synthase was determined by Western blot using specific antibodies for neuronal nitric oxide synthase and inducible nitric oxide synthase. Protein bands were detected by enhanced chemiluminescence, analyzed by imaging densitometry and the protein band density expressed as absorbance (OD x mm(2)). The density of neuronal nitric oxide synthase in the normoxic, hypoxic and hypoxic-7-nitro-indazole-sodium salt groups was: 41.56+/-4.27 in normoxic, 61.82+/-3.57 in hypoxic (P<0.05) and 47.80+/-1.56 in hypoxic-7-nitro-indazole-sodium salt groups (P=NS vs normoxic), respectively. Similarly, the density of inducible nitric oxide synthase in the normoxic, hypoxic and hypoxic-7-nitro-indazole-sodium salt groups was: 105.21+/-9.09, 157.71+/-13.33 (P<0.05 vx normoxic), 117.84+/-10.32 (p=NS vx normoxic), respectively. The data show that hypoxia results in increased expression of neuronal nitric oxide synthase and inducible nitric oxide synthase proteins in the cerebral cortex of newborn piglets and that the hypoxia-induced increased expression is prevented by the administration of 7-nitro-indazole-sodium salt. Furthermore, the neuronal nitric oxide synthase inhibition prevented the inducible nitric oxide synthase expression for a period of 7 days after hypoxia. Since administration of 7-nitro-indazole-sodium salt prevents nitric oxide generation by inhibiting neuronal nitric oxide synthase, we conclude that the hypoxia-induced increased expr

Topics: Adenosine Triphosphate; Animals; Animals, Newborn; Cell Death; Cerebral Cortex; Cerebral Infarction; Disease Models, Animal; Enzyme Activation; Enzyme Inhibitors; Hypoxia, Brain; Indazoles; Nerve Degeneration; Neurons; Nitric Oxide; Nitric Oxide Synthase Type I; Nitric Oxide Synthase Type II; Phosphocreatine; Sus scrofa; Up-Regulation

The impetus for the novel Energy Formula (EF) which combines the niacin-bound chromium (III) (0.45%) (NBC), standardized extract of Withania somnifera extracts (10.71%), caffeine (22.76%), D-ribose (10.71%) and selected amino acids such as phenylalanine, taurine and glutamine (55.37%) was based on the knowledge of the cardioprotective potentials of the Withania somnifera extract, caffeine and D-ribose as well as their abilities to increase energy levels and the abilities of amino acids to increase the muscle mass and energy levels. The effect of oral supplementation of EF on the safety, myocardial energy levels and cardioprotective ability were investigated in an ischemic-reperfused myocardium model in both male and female Sprague-Dawley rats over 90 days trial period. At the completion of 90 days, the EF-treated male and female rats gained 9.4% and 3.1% less body weights, respectively, as compared to their corresponding control groups. No significant difference was found in the levels of lipid peroxidation and activities of hepatic Aspartate transaminase, Alanine transaminase and Alkaline phosphatase in EF treatment when compared with control animals. The male and female rat hearts were subjected to 30 min of global ischemia followed by 2 h of reperfusion at 30 and 90 days of EF treatment. Cardiovascular functions including heart rate, coronary flow, aortic flow, dp/dt(max), left ventricular developed pressure (LVDP) and infarct size were monitored. The levels of myocardial adenosine triphosphate (ATP), creatine phosphate (CP), phospho-adenosine monophosphate kinase (p-AMPK) levels, were analyzed at the end of 30 and 90 days of treatment. Significant improvement was observed in all parameters in the EF treatment groups as compared to their corresponding controls. Thus the niacin-bound chromium (III) based energy formula is safe and effective supplement to boost energy levels and cardioprotection.

Topics: Adenosine Monophosphate; Adenosine Triphosphate; Animals; Apoptosis; Aspartate Aminotransferases; Blotting, Western; Body Weight; Chromium Compounds; Coronary Circulation; Dietary Supplements; Disease Models, Animal; Female; Heart Rate; Lipid Peroxidation; Male; Models, Biological; Myocardial Infarction; Myocardial Reperfusion Injury; Phosphocreatine; Phosphorylation; Protein Kinases; Rats; Rats, Sprague-Dawley

An animal model involving stepwise occlusion of the common carotid arteries (sCCAO) in DBA/2 mice is presented in which the right and left carotid arteries were permanently ligated within a time interval of four weeks. Thereafter, cerebral functional and structural parameters were determined at acute (15 min) and subchronic (1 day; 3, 7, and 14 days) time points after sCCAO. Quantitative changes in regional cerebral blood flow (rCBF) as determined by the [14C]iodoantipyrine method, energy state (ATP, phosphocreatine, ADP, AMP, adenosine) as shown by HPLC, brain histopathology, and neuronal densities were measured in both hemispheres. Acute sCCAO was accompanied by a drastic reduction in cerebral energy-rich phosphate concentrations, ATP and phosphocreatine, and in rCBF of more than 50%. In contrast, cortical adenosine increased around five-fold. Subchronic sCCAO, however, was associated with normalization in brain energy metabolites and near-complete restoration of rCBF, except in the caudate nucleus (-40%). No marked signs of necrotic or apoptotic cell destruction were detected. Thus, during the subchronic period, compensatory mechanisms are induced to counteract the drastic changes seen after acute vessel occlusion. In conclusion, this sCCAO mouse model may be useful for long-lasting investigations of stepwise deterioration contributing to chronic cerebrovascular disorders.

Topics: Adenosine; Adenosine Triphosphate; Animals; Biomarkers; Brain Ischemia; Carotid Stenosis; Cerebral Cortex; Cerebrovascular Circulation; Disease Models, Animal; Down-Regulation; Energy Metabolism; Female; Mice; Mice, Inbred DBA; Nerve Degeneration; Neurons; Oxidative Phosphorylation; Phosphocreatine; Up-Regulation

The mechanisms responsible for acute renal failure in sepsis are not understood. Measurement of tissue ATP might help to understand this process but, in the large animal, it is hampered by major technical difficulties.. To develop a technique to monitor ATP in the kidney of a large mammal during the induction of septic shock and then circulatory arrest.. Implantation of a custom-made phosphorus coil around the left kidney. Induction of septic shock by intravenous E. coli administration. Acquisition of 31 P magnetic resonance (MR) spectroscopic data at 3-tesla before and during septic shock over several hours. Induction of euthanasia and measurement of the same 31 P signal immediately and thirty minutes after circulatory arrest.. Clear reproducible 31 P MR spectra were obtained before and after the induction of septic shock and euthanasia. They indicated limited changes in ATP during septic shock. An expected rapid and dramatic decrease in ATP occurred with euthanasia.. It is possible to sequentially monitor renal bioenergetics in a large mammal during septic shock using an implanted custom-made phosphorus coil and 3-tesla MR technology. This technique offers a novel approach to the investigation of septic renal failure.

Topics: Acute Kidney Injury; Adenosine Triphosphate; Animals; Bacteremia; Disease Models, Animal; Escherichia coli Infections; Female; Kidney; Magnetic Resonance Spectroscopy; Phosphocreatine; Phosphorus Isotopes; Sheep; Shock; Shock, Septic; Thionucleotides

Aim of this study was to compare effects of BIIB-722, a novel Na(+)/H(+) exchanger-1 inhibitor, and ischemic preconditioning (IP) on infarct size and metabolism of area at risk in rats. Regional ischemia was induced by 40-min occlusion of a diagonal branch of left anterior descending coronary artery (LAD); it was followed by 60-min reperfusion. Intravenous bolus injection of BIIB-722 (3 mg/kg) dissolved in 280 mM xylitol was performed before regional ischemia or during the first minute of reperfusion. In the control group 280 mM xylitol was infused before ischemia or at the beginning of reperfusion at the same mode. IP was initiated by two cycles of 5-min LAD occlusion followed by 5-min reperfusion prior to sustained regional ischemia. Microdialysis technique was used to monitor pH and inorganic phosphate (P(i)) in the interstitial fluid of the area at risk. Metabolic state of the area at risk was assessed by ATP, phosphocreatine (PCr) and lactate levels; cellular membrane damage was evaluated by total creatine (SigmaCr=PCr+Cr) tissue content. Myocardial infarct size was determined by computer planimetry after staining of left ventricular slices with 2,3,5-triphenyltetrazolium chloride. BIIB-722 administration before or after ischemia, as well as IP, had no effect on cardiac hemodynamics and acid-base indices of arterial blood throughout the experiments. The infarct size/area at risk ratio was 43.5+/-5.2% in control and was reduced to 11.4+/-3.1% with IP, and to 17.0+/-3.6% and 25.8+/-2.6% with BIIB-722 infused on early reperfusion and before ischemia, respectively. BIIB-722 administration during the first minute of reperfusion as well as IP significantly augmented ATP and PCr contents, reduced lactate level and decreased ECr loss at the area at risk by the end of reperfusion as compared with values in control. Additionally significantly higher rates of pH recovery and reduction of P(i) concentration in the interstitial fluid were observed during reperfusion compared with these indices in control. BIIB-722 administration before ischemia had much effects on contents of energy and carbohydrate metabolites at area at risk. The results obtained indicate that ability of BIIB-722 to limit infarct size and improve metabolism in the area at risk is comparable to cardioprotective effects of IP. Therefore this study substantiates a possibility of application of a novel Na(+)/H(+) exchange inhibitor for clinical investigations.

Topics: Adenosine Triphosphate; Animals; Cation Transport Proteins; Disease Models, Animal; Guanidines; Injections, Intravenous; Ischemic Preconditioning, Myocardial; Lactic Acid; Male; Membrane Proteins; Myocardial Infarction; Myocardium; Phosphocreatine; Rats; Rats, Wistar; Sodium-Hydrogen Exchanger 1; Sodium-Hydrogen Exchangers; Treatment Outcome

Off pump coronary artery bypass grafting (OPCAB) involves, and is occasionally impaired by obligatory regional myocardial ischemia, particularly with the use of proximal coronary in-flow occlusion techniques. Intracoronary shunts do not guarantee absence of distal ischemia given their small inner diameter and the presence of proximal coronary stenosis. Additional adjunctive measures to provide short-term myocardial protection may facilitate OPCAB. High-energy phosphate supplementation with creatine phosphate prior to ischemia may attenuate ischemic dysfunction.. In a rodent model of a transient coronary occlusion and myocardial ischemia, 36 animals underwent preischemic intravenous infusion of either creatine phosphate or saline, 10 minutes of proximal left anterior descending (LAD) occlusion, and 10 minutes of reperfusion. Rats underwent continuous intracavitary pressure monitoring and cellular ATP levels were quantified using a luciferin/luciferase bioluminescence assay.. Within 2 minutes of ischemia onset, creatine phosphate animals exhibited statistically significant greater preservation of myocardial function compared to controls, an augmentation which persisted throughout the duration of ischemia and subsequent reperfusion. Furthermore, significantly greater cellular ATP levels were observed among creatine phosphate treated animals (344+/-55 nMol/g tissue, n=5) compared to control animals (160+/-9 nMol/g tissue, n=5)(p=0.014).. A strategy of intravenous high-energy phosphate administration successfully prevented ischemic ventricular dysfunction in a rodent model of OPCAB.

Topics: Adenosine Triphosphate; Animals; Cardiotonic Agents; Coronary Artery Bypass, Off-Pump; Disease Models, Animal; Infusions, Intravenous; Male; Myocardial Ischemia; Myocardium; Phosphocreatine; Rats; Rats, Wistar; Stroke Volume; Treatment Outcome; Troponin I

Early detection of delayed cerebral energy failure may be important in the prevention of reperfusion injury of the brain after severe perinatal hypoxia-ischaemia (HI). This study investigated whether monitoring of the redox state of cytochrome aa(3) (Cytaa(3)) with near infrared spectroscopy (NIRS) after severe perinatal asphyxia may allow us to detect early a compromised energy metabolism of the developing brain. We therefore correlated serial Cytaa(3) measurements (to estimate mitochondrial oxygenation) simultaneously with the (31)phosphorous-magnetic resonance spectroscopy ((31)P-MRS)-measured phosphocreatin/inorganic phosphate (PCr/Pi) ratio (to estimate cerebral energy reserve) in newborn piglets before and after severe hypoxia-ischaemia. The animals were treated upon reperfusion with either allopurinol, deferoxamine, or 2-iminobiotin or with a vehicle to reduce post-HI reperfusion injury of the brain. Four sham-operated piglets served as controls. Before HI, the individual Cytaa(3) values ranged between -0.02 and 0.71 micromol/L (mean value: -0.07) relative to baseline. The pattern over post-HI time of the vehicle-treated animals was remarkably different from the other groups in as far Cytaa(3) became more oxidised from 3 h after start of HI onwards (increase of Cytaa(3) as compared with baseline), whereas the other groups showed a significant reduction over time (decrease of Cytaa(3) as compared with baseline: allopurinol and deferoxamine) or hardly any change (2-iminobiotin and sham-operated piglets). Vehicle-treated piglets showed a significant reduction in PCr/Pi at 24 h after start of HI, but the cerebral energy state was preserved in 2-iminobiotin-, allopurinol- and deferoxamine-treated piglets. With severe reduction in PCr/Pi-ratio, major changes in the redox-state of Cytaa(3) also occurred: Cytaa(3) was mostly either in a reduced state (down to -6.45 micromol/L) or in an oxidised state (up to 6.84 micromol/L) at these low PCr/Pi ratios. The positive predictive value (PPV) of Cytaa(3) to predict severe reduction of the PCr/Pi ratio was 42%; the negative PPV was 87%. A similar relation was found for Cytaa(3) with histologically determined loss of neurons.

Topics: Allopurinol; Animals; Animals, Newborn; Biotin; Brain; Cell Survival; Deferoxamine; Disease Models, Animal; Disease Progression; Electron Transport Complex IV; Energy Metabolism; Free Radical Scavengers; Hypoxia-Ischemia, Brain; Iron Chelating Agents; Magnetic Resonance Spectroscopy; Neurons; Neuroprotective Agents; Oxidation-Reduction; Phosphates; Phosphocreatine; Predictive Value of Tests; Spectroscopy, Near-Infrared; Swine

Data show that uptake of amino acids correlates with myocardial oxygen consumption after aortic cross-clamp in humans; this suggests a direct link between amino acids and myocardial energy metabolism. The aim of this preliminary study was to investigate the anti-ischemic effects of immediate and long-term supplementation of an amino acid mixture. We tested this hypothesis on isolated rats hearts subjected to global ischemia for 30 minutes. Long-term treatment with an amino acid mixture achieved the following: (1) reduced the increase of diastolic pressure (48 +/- 3 mm Hg vs 21 +/- 4 mm Hg; p <0.05); (2) maintained the tissue content of adenosine triphosphate during ischemia (2.5 +/- 0.6 micromol/g wet wt [gww] vs 7.0 +/- 1.2 micromol/gww; p <0.05); and (3) improved the recovery of developed pressure at the end of postischemic reperfusion (11 +/- 2 mm Hg vs 38 +/- 3 mm Hg; p <0.05), reducing the release of creatine kinase (375 +/- 30 microU/min/gww vs 196 +/- 15 microU/min/gww; p <0.05) and lactate (15 +/- 1.5 mg/min/gww vs 5 +/- 1 mg/min/gww; p <0.05). We conclude that long-term supplementation of an amino acid mixture reduced myocardial ischemic damage.

Topics: Adenosine Triphosphate; Administration, Oral; Amino Acids, Essential; Animals; Creatine Kinase; Dietary Proteins; Dietary Supplements; Disease Models, Animal; Lactic Acid; Male; Myocardial Ischemia; Myocardium; Phosphocreatine; Rats; Rats, Sprague-Dawley; Ventricular Function, Left

Cerebral hypoxia-ischemia (HI) is an important cause of perinatal brain damage in the term newborn. The areas most affected are the parasagittal regions of the cerebral cortex and, in severe situations, the basal ganglia. The aim of this study was to show that the newborn piglet model can be used to produce neuropathology resulting from moderate HI insult and to monitor damage for 7 days. Two acute cerebral HI were induced in newborn Large White piglets by reducing the inspired oxygen fraction to 4% and occluding the carotid arteries. Newborn piglets were resuscitated, extubated and monitored for 7 days. (31)P magnetic resonance spectroscopy (MRS) offers the ability to monitor the severity of the HI insults. Lactate (Lac) was detected in the HI group at 2 h, 3 days and 5 days after insult by (1)H MRS. Lac/n-acetylaspartate and Lac/choline and Lac/creatine ratios increased significantly (p < 0.01) in the HI group 2 h after HI insults and remained high over 7 days. For the HI group, mean T(2) values increased significantly in the parietal white matter (subcortical) for 5 days after HI insult [117.5 (+/-7.4) to 158.5 (+/-19.2) at T+3 days, 167.7 (+/-15.4) at T+5 days and 160.9 (+/-10.1) at T+7 days (p < 0.01)]. This newborn piglet model of moderate HI brain injury with reproducible cerebral damage could be use as reference for the study of neuroprotective strategy for a period of 7 days.

Topics: Animals; Animals, Newborn; Aspartic Acid; Basal Ganglia; Cerebral Cortex; Cerebrovascular Circulation; Disease Models, Animal; Energy Metabolism; Hydrogen; Hydrogen-Ion Concentration; Hypoxia-Ischemia, Brain; Ischemic Attack, Transient; Lactic Acid; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Phosphocreatine; Phosphorus Isotopes; Radiopharmaceuticals; Severity of Illness Index; Stroke; Swine

To determine whether epinephrine increases lactate concentration in sepsis through hypoxia or through a particular thermogenic or metabolic pathway.. Prospective, controlled experimental study in rats.. Experimental laboratory in a university teaching hospital.. Three groups of anesthetized, mechanically ventilated male Wistar rats received an intravenous infusion of 15 mg/kg Escherichia coli O127:B8 endotoxin. Rats were treated after 90 min by epinephrine ( n=14), norepinephrine ( n=14), or hydroxyethyl starch ( n=14). Three groups of six rats served as time-matched control groups and received saline, epinephrine, or norepinephrine from 90 to 180 degrees min. Mean arterial pressure, aortic, renal, mesenteric and femoral blood flow, arterial blood gases, lactate, pyruvate, and nitrate were measured at baseline and 90 and 180 min after endotoxin challenge. At the end of experiments biopsy samples were taken from the liver, heart, muscle, kidney, and small intestine for tissue adenine nucleotide and lactate/pyruvate measurements.. Endotoxin induced a decrease in mean arterial pressure and in aortic, mesenteric, and renal blood flow. Plasmatic and tissue lactate increased with a high lactate/pyruvate (L/P) ratio. ATP decreased in liver, kidney, and heart. The ATP/ADP ratio did not change, and phosphocreatinine decreased in all organs. Epinephrine and norepinephrine increased mean arterial pressure to baseline values. Epinephrine increased aortic blood flow while renal blood low decreased with both drugs. Plasmatic lactate increased with a stable L/P ratio with epinephrine and did not change with norepinephrine compared to endotoxin values. Nevertheless epinephrine and norepinephrine when compared to endotoxin values did not change tissue L/P ratios or ATP concentration in muscle, heart, gut, or liver. In kidney both drugs decreased ATP concentration.. Our data demonstrate in a rat model of endotoxemia that epinephrine-induced hyperlactatemia is not related to cellular hypoxia.

Topics: Acidosis, Lactic; Adenosine Diphosphate; Adenosine Triphosphate; Animals; Blood Gas Analysis; Disease Models, Animal; Drug Evaluation, Preclinical; Endotoxemia; Energy Metabolism; Epinephrine; Escherichia coli Infections; Glycolysis; Hemodynamics; Humans; Kidney; Lactic Acid; Liver; Myocardium; Nitrates; Norepinephrine; Phosphocreatine; Pyruvates; Rats; Rats, Wistar; Tissue Distribution

Compared with normal hearts, those with pathology (hypertrophy) are less tolerant of metabolic stresses such as ischemia. Pharmacologic intervention administered prior to such stress could provide significant protection. This study determined, firstly, whether the pentose sugar ribose, previously shown to improve postischemic recovery of energy stores and function, protects against ischemia when administered as a pretreatment. Secondly, the efficacy of this same pretreatment protocol was determined in hearts with pathology (hypertrophy). For study 1, Sprague-Dawley rats received equal volumes of either vehicle (bolus i.v. saline) or ribose (100 mg/kg) before global myocardial ischemia. In study 2, spontaneously hypertensive rats (SHR; blood pressure approximately 200/130) with myocardial hypertrophy underwent the same treatment protocol and assessments. In vivo left ventricular function was measured and myocardial metabolites and tolerance to ischemia were assessed. In normal hearts, ribose pretreatment significantly elevated the heart's energy stores (glycogen), and delayed the onset of irreversible ischemic injury by 25%. However, in vivo ventricular relaxation was reduced by 41% in the ribose group. In SHR, ribose pretreatment did not produce significant elevations in the heart's energy or improvements in tolerance to global ischemia, but significantly improved ventricular function (maximal rate of pressure rise (+dP/dt(max)), 25%; normalized contractility ((+dP/dt)/P), 13%) despite no change in hemodynamics. Thus, administration of ribose in advance of global myocardial ischemia does provide metabolic benefit in normal hearts. However, in hypertrophied hearts, ribose did not affect ischemic tolerance but improved ventricular function.

Topics: Adenosine Triphosphate; Anaerobic Threshold; Animals; Cardiotonic Agents; Disease Models, Animal; Drug Administration Schedule; Glycogen; Hypertension; Hypertrophy, Left Ventricular; Injections, Intravenous; Male; Myocardial Ischemia; Myocardium; Phosphocreatine; Rats; Rats, Sprague-Dawley; Ribose; Structure-Activity Relationship; Ventricular Function, Left; Ventricular Function, Right

Although high-energy phosphate metabolism is abnormal in failing hearts [congestive heart failure (CHF)], it is unclear whether oxidative capacity is impaired. This study used the mitochondrial uncoupling agent 2,4-dinitrophenol (DNP) to determine whether reserve oxidative capacity exists during the high workload produced by catecholamine infusion in hypertrophied and failing hearts. Left ventricular hypertrophy (LVH) was produced by ascending aortic banding in 21 swine; 9 animals developed CHF. Basal myocardial phosphocreatine (PCr)/ATP measured with 31P NMR spectroscopy was decreased in both LVH and CHF hearts (corresponding to an increase in free [ADP]), whereas ATP was decreased in hearts with CHF. Infusion of dobutamine and dopamine (each 20 microg. kg-1. min-1 iv) caused an approximate doubling of myocardial oxygen consumption (MVO2) in all groups and decreased PCr/ATP in the normal and LVH groups. During continuing catecholamine infusion, DNP (2-8 mg/kg iv) caused further increases of MVO2 in normal and LVH hearts with no change in PCr/ATP. In contrast, DNP caused no increase in MVO2 in the failing hearts; the associated decrease of PCr/ATP suggests that DNP decreased the mitochondrial proton gradient, thereby causing ADP to increase to maintain adequate ATP synthesis.

Topics: Adenosine Triphosphate; Animals; Coronary Circulation; Disease Models, Animal; Heart Failure; Hypertrophy, Left Ventricular; Magnetic Resonance Spectroscopy; Mitochondria; Myocardium; Oxygen Consumption; Phosphocreatine; Protons; Sus scrofa

Methylmalonic acidemias are metabolic disorders caused by a severe deficiency of methylmalonyl-CoA mutase activity, which are characterized by neurological dysfunction, including convulsions. It has been reported that the accumulating metabolite, L-methylmalonic acid (MMA), inhibits succinate dehydrogenase leading to ATP depletion in vitro, and that the intrastriatal injection of MMA induces convulsions through secondary NMDA receptor stimulation. In this study we investigated the effect of creatine (1.2, 3.6 and 12.0 mg/kg, (i.p.), [DOSAGE ERROR CORRECTED] succinate (1.5 micromol/striatum) and MK-801 (3 nmol/striatum) on the convulsions and on the striatal lactate increase induced by MMA (4.5 micromol/striatum) in rats. The effect of creatine on the striatal phosphocreatine content and on MMA-induced phosphocreatine depletion was also evaluated. Creatine, succinate and MK-801 pretreatment decreased the number and duration of convulsive episodes and the lactate increase elicited by MMA. Creatine, but not succinate, prevented the convulsions and the lactate increase induced by the direct stimulation of NMDA receptors. Acute creatine administration increased the total striatal phosphocreatine content and prevented MMA-induced phosphocreatine depletion. Our results suggest that MMA increases lactate production through secondary NMDA receptor activation, and it is proposed that the anticonvulsant effect of creatine against MMA-induced convulsions may be due to an increase in the phosphocreatine content available for metabolic purposes.

Topics: Animals; Behavior, Animal; Corpus Striatum; Creatine; Disease Models, Animal; Dizocilpine Maleate; Dose-Response Relationship, Drug; Excitatory Amino Acid Agonists; Excitatory Amino Acid Antagonists; Lactic Acid; Male; Methylmalonic Acid; N-Methylaspartate; Phosphocreatine; Radiation-Protective Agents; Rats; Rats, Wistar; Seizures; Succinic Acid

Previous studies have shown that hypoxia results in increased Ca2+ influx in neuronal nuclei and generation of nitric oxide (NO) free radicals in the cerebral cortical tissue of newborn piglets. The present study tests the hypothesis that hypoxia results in modification of the inositol triphosphate (IP3) receptor characteristics in neuronal nuclei and that the hypoxia-induced modification of the IP3 receptor is NO mediated. Studies were performed in piglets, 3-5 days old, divided into normoxic (n = 5), hypoxic (n = 5), and NO synthase (NOS) inhibitor N-nitro-L-arginine (NNLA)-treated hypoxic (n = 5) groups. The NNLA-treated hypoxic group received an infusion of NNLA (40 mg/kg) over 1 hr prior to hypoxic exposure. The hypoxia was induced by lowering the FiO2 to 0.05-0.07 for 1 hr. Brain tissue hypoxia was documented biochemically by determining ATP and phosphocreatine (PCr) levels. Neuronal nuclei were isolated from the cerebral cortical tissue, and IP3 receptor binding was performed in a medium containing 50 mM HEPES (pH 8.0), 2 mM EDTA, 3H-IP3 (7.5-100 nM), and 100 microg nuclear protein. Nonspecific binding was determined in the presence of 10 microM unlabelled IP3. The IP3 receptor characteristics Bmax (number of receptor sites) and Kd (dissociation constant) were determined. In normoxic, hypoxic, and NNLA-hypoxic groups, ATP levels were 4.46 +/- 0.35, 1.52 +/- 0.10 (P <.05 vs. normoxic), and 1.96 +/- 0.33 micromoles/g brain, respectively (P <.05 vs. normoxic). PCr levels were 3.75 +/- 0.35, 0.87 +/- 0.09 (P <.05 vs. normoxic), and 1.31 +/- 0.10 micromoles/g brain, respectively (P <.05 vs. normoxic). IP3 receptor binding characteristics in normoxic nuclear membranes showed that the Bmax value was 150.0 +/- 14.1 pmoles/mg protein compared with 239.3 +/- 13.6 pmoles/mg protein in the hypoxic group (P <.05). In the NNLA-treated hypoxic group, the Bmax value was 159.0 +/- 42.6 pmoles/mg protein (P <.05 vs. hypoxic a, P = NS vs. normoxic). Similarly, the Kd was 25.2 +/- 0.28 nM in the normoxic group, 44.6 +/- 5.4 nM in the hypoxic group (P <.05), and 28.1 +/- 6.4 nM in the NNLA-treated hypoxic group. (P <.05 vs. hypoxic and P = NS vs. normoxic). The results show that hypoxia results in increased Bmax and Kd values for the IP3 receptor. Furthermore, the data demonstrate that administration of NNLA prior to hypoxia prevents the hypoxia-induced modification of the IP3 receptor in neuronal nuclei of newborn piglets. Because NNLA inhibits NOS and prevents genera

Topics: Adenosine Triphosphate; Animals; Animals, Newborn; Binding Sites; Calcium; Calcium Channels; Calcium Signaling; Cell Death; Cell Nucleus; Disease Models, Animal; Enzyme Inhibitors; Hypoxia, Brain; Inositol 1,4,5-Trisphosphate Receptors; Neurons; Nitric Oxide; Nitric Oxide Synthase; Phosphocreatine; Receptors, Cytoplasmic and Nuclear; Sus scrofa

High-energy phosphate metabolism is altered in the ischemic myocardium. We investigated the effects of in vivo administration of phosphocreatine (PCr) in a transient ischemic rat model to emulate off-pump myocardial revascularization.. Rats received either PCr (100 mg/kg) or saline intravenously 1 hour before surgery. Regional ischemia was maintained for 12 minutes by ligation of the left anterior descending artery and compared with sham-operated animals. Cardiac tissue was studied for ATP, PCr, and inorganic phosphate (Pi) using (31)P-cryo-NMR. Results were compared by ANOVA.. Levels of ATP were significantly (p < 0.01) lower in the ischemic hearts compared with controls; Pi and PCr remained unchanged. The PCr/Pi ratio was altered in ischemic hearts, reflecting an increased energy demand. PCr administration significantly (p < 0.01) elevated the content of PCr and ATP in both normal and ischemic hearts.. PCr restores high-energy phosphates and attenuates metabolic stress during periods of myocardial ischemia in the rat. Preconditioning with PCr may serve as a useful adjunct to off-pump coronary revascularization.

Topics: Adenosine Triphosphate; Analysis of Variance; Animals; Coronary Vessels; Disease Models, Animal; Drug Evaluation, Preclinical; Energy Metabolism; Glycolysis; Injections, Intravenous; Ischemic Preconditioning, Myocardial; Ligation; Magnetic Resonance Imaging; Male; Myocardial Ischemia; Myocardial Reperfusion; Myocardium; Phosphates; Phosphocreatine; Phosphorus Isotopes; Phosphorylation; Rats; Rats, Sprague-Dawley; Time Factors

In a Sham-controlled study we applied proton magnetic resonance spectroscopy (1H-MRS) at 4.7 T to a model of experimental traumatic brain contusion. The time course of cerebral metabolite changes was monitored in serial investigation in 14 Sprague Dawley rats up to 4 weeks after trauma. 6 animals served as controls. 1H-MRS spectra were acquired from a voxel covering the hippocampus/basal ganglia ipsi and contralateral to the lesion. Metabolites ratios of the injured hemisphere were compared to those ipsilateral in Sham animals and to those of the contralateral side in the trauma animals. NAA/Cr ratio and Glu/Cr ratio, possible markers of neuronal loss, persistently decreased after trauma to a minimum of -40% and -20% versus controls, respectively. One week after trauma Cho/Cr ratio was strongly increased by 73%. This might indicate a high inflammatory activity at that time. Lac/Cr ratio showed long-lasting and continuing increases up to 2000% versus controls as a sign of permanently shifted posttraumatic energy metabolism. 1H-MRS proved to be a useful non-invasive method for in-vivo monitoring of posttraumatic metabolism also in models of brain contusion. In single cases however, accompanying haemorrhage can potentially prevent useful data acquisition.

Topics: Animals; Aspartic Acid; Basal Ganglia; Biomarkers; Brain; Brain Injuries; Disease Models, Animal; Functional Laterality; Glutamic Acid; Hippocampus; Lactates; Magnetic Resonance Imaging; Male; Monitoring, Physiologic; Phosphocreatine; Rats; Rats, Sprague-Dawley; Reference Values; Taurine; Time Factors

This study evaluates the effects of diltiazem administered during reperfusion on hemodynamic, metabolic, and ultrastructural postischemic outcome.. Hearts of 38 adult White New Zealand rabbits underwent 60 min of global cold ischemia followed by 40 min of reperfusion in an erythrocyte perfused isolated working heart model. Hearts were randomly assigned to four groups and received diltiazem (0.1, 0.25, and 0.5 micromol/l) during reperfusion only, or served as control.. The postischemic time courses of heart rate, aortic flow, and external stroke work clearly reflected the dose-dependent negative chronotropic and inotropic efficacy of diltiazem in the two higher concentrations. High energy phosphates (HEP) determined from myocardial biopsies taken after 40 min of reperfusion were significantly better preserved in all treatment groups compared to control hearts. Similarly ultrastructural grading of mitochondria and myofilaments revealed a significant reduction of reperfusion injury in hearts that received diltiazem compared to control.. Diltiazem protects mitochondrial integrity and function, thereby preserving myocardial HEP levels. Only low dose diltiazem (0.1 micromol/l) during reperfusion combines both, optimal mitochondrial preservation with minimal changes in hemodynamics.

Topics: Adenine Nucleotides; Analysis of Variance; Animals; Biopsy, Needle; Chromatography, High Pressure Liquid; Diltiazem; Disease Models, Animal; Female; Hemodynamics; Male; Mitochondria, Heart; Myocardial Ischemia; Myocardial Reperfusion; Phosphocreatine; Probability; Rabbits; Random Allocation; Reference Values; Reperfusion Injury; Sensitivity and Specificity

Reports have attributed cardiac failure during acute models of endotoxemia to a lack of high-energy phosphates. This study was undertaken to investigate whether creatine (Cr) administered during perfusion could enhance myocardial protection and improve recovery of cardiac function in a rat model of endotoxemia.. Acute endotoxemia was induced in rats by a bolus injection of Escherichia coli endotoxin (LPS: 4 mg/kg, ip) while control rats were injected with an equal volume of 0.9% normal saline. To assess the adequacy of energy metabolism, freeze-clamped hearts were obtained from animals to study the concentrations of endogenous ATP, phosphocreatine (PCr), inorganic phosphate (P(i)), and intracellular pH by (31)P-cryomagnetic resonance spectroscopy. In a separate experiment, isolated hearts were perfused via a Langendorff column with Krebs-Henseleit buffer containing different concentrations of creatine monohydrate (1, 3, or 10 mM). Cardiac performance was evaluated via a paced (300 bpm) isovolumetric balloon preparation. Measurements of cardiac function including left ventricular developed pressure (LVDP), the maximum rates of ventricular pressure rise (LV +dP/dt) and fall (LV -dP/dt), and coronary flow were made for both LPS and saline-treated animals.. High-energy phosphate ratios of PCr/ATP and PCr/P(i) in hearts declined significantly at 4 h after endotoxin treatment. As anticipated, LVDP and LV +dP/dt(max) at a given preload and heart rate were significantly (P < 0.05) lower at 4 h when measured at the same time point. The functional recovery of these parameters was not improved by the addition of creatine monohydrate to the perfusion buffer. Creatine produced a significant (P < 0.05) negative inotropic effect in hearts from saline-treated animals. The LVDP was reduced by 30% at the lowest concentration and by 50% at the highest concentration of creatine monohydrate. Furthermore, creatine significantly (P < 0.05) reduced LV -dP/dt(max) in both saline and LPS-treated rats. These data demonstrate that exogenous creatine does not contribute to myocardial preservation in endotoxemia.. Energy stores in the rat heart decline early in endotoxemia accompanied by reduced myocardial performance, suggesting that the ability of the heart to perform mechanical work is impaired. Cardiac dysfunction in an acute model of endotoxemia was not improved with exogenous creatine during perfusion. Creatine's effects were primarily lusitropic by delaying the onset of myocardial relaxation in all hearts. The deleterious effects of exogenous creatine monohydrate in normal hearts should be examined in future experimental studies.

Topics: Adenosine Triphosphate; Animals; Cardiomyopathies; Creatine; Disease Models, Animal; Endotoxemia; In Vitro Techniques; Lipopolysaccharides; Magnetic Resonance Spectroscopy; Male; Myocardium; Phosphocreatine; Rats; Rats, Sprague-Dawley; Specific Pathogen-Free Organisms; Ventricular Pressure

Topics: Adenosine Triphosphate; Animals; Aortic Valve Insufficiency; Atrial Natriuretic Factor; Blotting, Northern; Cardiac Output, Low; Disease Models, Animal; Humans; Ion Channels; Male; Membrane Transport Proteins; Mitochondria, Heart; Mitochondrial Proteins; Muscle, Skeletal; Myocardium; Phosphocreatine; Proteins; Rats; Rats, Sprague-Dawley; RNA, Messenger; Tumor Necrosis Factor-alpha; Uncoupling Agents; Uncoupling Protein 2

This study examined high-energy phosphates (HEP) and mitochondrial ATPase protein expression in hearts in which myocardial infarction resulted in either compensated left ventricular remodeling (LVR) or congestive heart failure (CHF). The response of HEP (measured via (31)P magnetic resonance spectroscopy) to a modest increase in the cardiac work state produced by dobutamine-dopamine infusion and pacing (if needed) was examined in 17 pigs after left circumflex coronary artery ligation (9 with LVR and 8 with CHF) and compared with 7 normal pigs. In hearts with LVR, the baseline phosphocreatine (PCr)-to-ATP ratio decreased, and calculated ADP increased; these changes were most severe in hearts with CHF. HEP levels did not change in normal or LVR hearts during dobutamine-dopamine infusion. However, in hearts with CHF, the PCr-to-ATP ratio decreased further, and free ADP increased. The mitochondrial protein levels of the F(0)F(1)-ATPase subunits were normal in hearts with compensated LVR. However, in failing hearts, the alpha-subunit decreased by 36%, the beta-subunit decreased by 16%, the oligomycin sensitivity-conferring protein subunit decreased by 40%, and the initiation factor 1 subunit decreased by 41%. Thus in failing hearts, reductions in mitochondrial F(0)F(1)-ATPase protein expression are associated with increased myocardial free ADP.

Topics: Adenosine Diphosphate; Adenosine Triphosphate; Animals; Body Weight; Cardiac Pacing, Artificial; Coronary Circulation; Disease Models, Animal; Dobutamine; Dopamine; Heart Failure; Hemodynamics; Infusions, Intravenous; Magnetic Resonance Spectroscopy; Mitochondria, Heart; Myocardial Infarction; Organ Size; Phosphocreatine; Protein Subunits; Proton-Translocating ATPases; Swine; Ventricular Remodeling

Tumor necrosis factor (TNF)-alpha has been implicated in the pathogenesis of heart failure and ischemia-reperfusion injury. Effects of TNF-alpha are initiated by membrane receptors coupled to sphingomyelinase signaling and include altered metabolism and calcium cycling, contractile dysfunction, and cell death. We postulate that pressure-overload hypertrophy results in increased myocardial TNF-alpha expression and that it contributes to decreased contractility in hypertrophied infant hearts subjected to ischemia-reperfusion.. Neonatal rabbits underwent aortic banding to induce LV hypertrophy. Myocardial TNF-alpha protein expression increased progressively with LV hypertrophy. Serum TNF-alpha was detected only after the onset of heart failure. Before onset of ventricular dilatation and heart failure (determined by serial echocardiograms), hearts from aortic banded and age-matched control rabbits were perfused in the Langendorff mode and subjected to 45 minutes of ischemia and 30 minutes of reperfusion. Postischemic recovery was impaired in hypertrophied hearts, but addition of neutralizing anti-rabbit TNF-alpha antibody to cardioplegia and perfusate solutions restored postischemic function. This effect was mimicked by treatment with the ceramidase inhibitor N-oleoyl ethanolamine. TNF-alpha inhibition also was associated with faster postischemic recovery of phosphocreatine, ATP, and pH as assessed by (31)P nuclear magnetic resonance spectroscopy. Intracellular calcium handling, measured by Rhod 2 spectrofluorometry, demonstrated lower diastolic calcium levels and higher systolic calcium transients in anti-TNF-alpha treated hearts.. TNF-alpha is expressed in myocardium during compensated pressure-overload hypertrophy and contributes to postischemic myocardial dysfunction. Inhibition of TNF-alpha signaling significantly improves postischemic contractile function, myocardial energetics, and intracellular calcium handling.

Topics: Adenosine Triphosphate; Animals; Animals, Newborn; Antibodies; Calcium; Diastole; Disease Models, Animal; Enzyme Inhibitors; Fluorescent Dyes; Heart; Heterocyclic Compounds, 3-Ring; Hydrogen-Ion Concentration; Hypertrophy, Left Ventricular; In Vitro Techniques; Intracellular Fluid; Magnetic Resonance Spectroscopy; Myocardial Contraction; Myocardial Ischemia; Myocardium; Organ Size; Phosphocreatine; Rabbits; Systole; Tumor Necrosis Factor-alpha; Ventricular Function, Left

The failing myocardium is characterized by reductions of phosphocreatine (PCr) and free creatine content and by decreases of energy reserve via creatine kinase (CK), ie, CK reaction velocity (Flux(CK)). It has remained unclear whether these changes contribute directly to contractile dysfunction. In the present study, myocardial PCr stores in a heart failure model were further depleted by feeding of the PCr analogue beta-guanidinopropionate (GP). Functional and metabolic consequences were studied.. Rats were subjected to sham operation or left coronary artery ligation (MI). Surviving rats were assigned to 4 groups and fed with 0% (n=7, Sham; n=5, MI) or 1% (n=7 Sham+GP, n=8 MI+GP) GP. Two additional groups were fed GP for 2 or 4 weeks before MI. After 8 weeks, hearts were isolated and perfused, and left ventricular pressure-volume curves were obtained. High-energy phosphate metabolism was determined with (31)P NMR spectroscopy. After GP feeding or MI, left ventricular pressure-volume curves were depressed by 33% and 32%, respectively, but GP feeding in MI hearts did not further impair mechanical function. Both MI and GP feeding reduced PCr content and Flux(CK), but here, effects were additive. In MI+GP rats, PCr levels and Flux(CK) were reduced by 87% and 94%, respectively. Although ATP levels were maintained in the GP and MI groups, ATP content was reduced by 18% in MI+GP hearts. Furthermore, 24-hour mortality in GP-prefed rats was 100%.. Rats with an 87% predepletion of myocardial PCr content cannot survive an acute MI. Chronically infarcted hearts subjected to additional PCr depletion cannot maintain ATP homeostasis.

Topics: Adenosine Triphosphate; Animals; Blood Flow Velocity; Body Weight; Chronic Disease; Coronary Circulation; Coronary Vessels; Disease Models, Animal; Guanidines; Heart; Heart Rate; Homeostasis; In Vitro Techniques; Ligation; Magnetic Resonance Spectroscopy; Myocardial Infarction; Organ Size; Phosphocreatine; Phosphorus Isotopes; Propionates; Rats; Rats, Wistar; Survival Rate; Ultrasonography; Ventricular Function, Left

Vascular endothelial growth factor (VEGF) is known to play an important role in angiogenesis. Its place in collateral artery growth (arteriogenesis), however, is still debated. In the present study, we analyzed the expression of VEGF and its receptors (Flk-1 and Flt-1) in a rabbit model of collateral artery growth after femoral artery occlusion. Hypoxia presents the most important stimulus for VEGF expression. We therefore also investigated the expression level of distinct hypoxia-inducible genes (HIF-1alpha, LDH A) and determined metabolic intermediates indicative for ischemia (ATP, creatine phosphate, and their catabolites). We found that arteriogenesis was not associated with an increased expression of VEGF or the mentioned hypoxia-inducible genes. Furthermore, the high-energy phosphates and their catabolites were entirely within normal limits. Despite the absence of an increased expression of VEGF and its receptors, collateral vessels increased their diameter by a factor of 10. The speed of collateral development could be increased by infusion of the chemoattractant monocyte chemotactic protein-1 but not by infusion of a 30 times higher concentration of VEGF. From these data, we conclude that under nonischemic conditions, arteriogenesis is neither associated with nor inducible by increased levels of VEGF and that VEGF is not a natural agent to induce arteriogenesis in vivo.

Topics: Adenosine Triphosphate; Animals; Arterial Occlusive Diseases; Cells, Cultured; Chemokine CCL2; Collateral Circulation; Disease Models, Animal; Endothelial Growth Factors; Female; Femoral Artery; Gene Expression Regulation; Hemodynamics; Hypoxia; Ischemia; Isoenzymes; L-Lactate Dehydrogenase; Lactate Dehydrogenase 5; Ligation; Lymphokines; Male; Muscle, Skeletal; Neovascularization, Pathologic; Phosphocreatine; Proto-Oncogene Proteins; Rabbits; Receptor Protein-Tyrosine Kinases; Receptors, Growth Factor; Receptors, Vascular Endothelial Growth Factor; RNA, Messenger; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factor Receptor-1; Vascular Endothelial Growth Factors; Vascular Patency

Intrastriatal injection of quinolinic acid (QA) provides an animal model of Huntington disease. In vivo (1)H NMR spectroscopy was used to measure the neurochemical profile non-invasively in seven animals 5 days after unilateral injection of 150 nmol of QA. Concentration changes of 16 metabolites were measured from 22 microl volume at 9.4 T. The increase of glutamine ((+25 +/- 14)%, mean +/- SD, n = 7) and decrease of glutamate (-12 +/- 5)%, N-acetylaspartate (-17 +/- 6)%, taurine (-14 +/- 6)% and total creatine (-9 +/- 3%) were discernible in each individual animal (P < 0.005, paired t-test). Metabolite concentrations in control striata were in excellent agreement with biochemical literature. The change in glutamate plus glutamine was not significant, implying a shift in the glutamate-glutamine interconversion, consistent with a metabolic defect at the level of neuronal-glial metabolic trafficking. The most significant indicator of the lesion, however, were the changes in glutathione ((-19 +/- 9)%, P < 0.002)), consistent with oxidative stress. From a comparison with biochemical literature we conclude that high-resolution in vivo (1)H NMR spectroscopy accurately reflects the neurochemical changes induced by a relatively modest dose of QA, which permits one to longitudinally follow mitochondrial function, oxidative stress and glial-neuronal metabolic trafficking as well as the effects of treatment in this model of Huntington disease.

Topics: Amino Acids; Animals; Cell Death; Disease Models, Animal; Dose-Response Relationship, Drug; Energy Metabolism; Female; Glucose; Huntington Disease; Magnetic Resonance Spectroscopy; Mitochondria; Neostriatum; Neuroglia; Neurons; Neurotoxins; Oxidative Stress; Phosphocreatine; Quinolinic Acid; Rats; Rats, Inbred F344

Our goals were to (1) simulate the degree of low-flow ischemia and mixed anaerobic and aerobic metabolism of an acutely infarcting region; (2) define changes in anaerobic glycolysis, oxidative phosphorylation, and the creatine kinase (CK) reaction velocity; and (3) determine whether and how increased glycolytic substrate alters the energetic profile, function, and recovery of the ischemic myocardium in the isolated blood-perfused rat heart.. Hearts had 60 minutes of low-flow ischemia (10% of baseline coronary flow) and 30 minutes of reperfusion with either control or high glucose and insulin (G+I) as substrate. In controls, during ischemia, rate-pressure product and oxygen consumption decreased by 84%. CK velocity decreased by 64%; ATP and phosphocreatine (PCr) concentrations decreased by 51% and 63%, respectively; inorganic phosphate (P(i)) concentration increased by 300%; and free [ADP] did not increase. During ischemia, relative to controls, the G+I group had similar CK velocity, oxygen consumption, and tissue acidosis but increased glycolysis, higher [ATP] and [PCr], and lower [P(i)] and therefore had a greater free energy yield from ATP hydrolysis. Ischemic systolic and diastolic function and postischemic recovery were better.. During low-flow ischemia simulating an acute myocardial infarction region, oxidative phosphorylation accounted for 90% of ATP synthesis. The CK velocity fell by 66%, and CK did not completely use available PCr to slow ATP depletion. G+I, by increasing glycolysis, slowed ATP depletion, maintained lower [P(i)], and maintained a higher free energy from ATP hydrolysis. This improved energetic profile resulted in better systolic and diastolic function during ischemia and reperfusion. These results support the clinical use of G+I in acute MI.

Topics: Adenosine Triphosphate; Animals; Creatine Kinase; Disease Models, Animal; Glucose; Hemodynamics; Insulin; Magnetic Resonance Spectroscopy; Male; Myocardial Infarction; Myocardial Ischemia; Myocardium; Oxidative Phosphorylation; Oxygen Consumption; Phosphocreatine; Rats; Rats, Wistar

Hypoxia and reoxygenation were studied in rat hearts and ischemia and reperfusion in rat hindlimbs. Free radicals are known to be generated through these events and to propagate complications. In order to reduce hypoxic/ischemic and especially reoxygenation/reperfusion injury the (re)perfusion conditions were ameliorated including the treatment with antioxidants (lipoate or dihydrolipoate). In isolated working rat hearts cardiac and mitochondrial parameters are impaired during hypoxia and partially recover in reoxygenation. Dihydrolipoate, if added into the perfusion buffer at 0.3 microM concentration, keeps the pH higher (7. 15) during hypoxia as compared to controls (6.98). The compound accelerates the recovery of the aortic flow and stabilizes it during reoxygenation. With dihydrolipoate, ATPase activity is reduced, ATP synthesis is increased and phosphocreatine contents are higher than in controls. Creatine kinase activity is maintained during reoxygenation in the dihydrolipoate series. Isolated rat hindlimbs were stored for 4 h in a moist chamber at 18 degrees C. Controls were perfused for 30 min with a modified Krebs-Henseleit buffer at 60 mmHg followed by 30 min Krebs-Henseleit perfusion at 100 mmHg. The dihydrolipoate group contained 8.3 microM in the modified reperfusate (controlled reperfusion). With dihydrolipoate, recovery of the contractile function was 49% (vs. 34% in controls) and muscle flexibility was maintained whereas it decreased by 15% in the controls. Release of creatine kinase was significantly lower with dihydrolipoate treatment. Dihydrolipoate effectively reduces reoxygenation injury in isolated working rat hearts. Controlled reperfusion, including lipoate, prevents reperfusion syndrome after extended ischemia in exarticulated rat hindlimbs and in an in vivo pig hindlimbs model.

Topics: Adenosine Triphosphatases; Animals; Creatine Kinase; Disease Models, Animal; Heart; Hindlimb; In Vitro Techniques; Male; Muscle Contraction; Myocardial Ischemia; Myocardial Reperfusion Injury; Myocardium; Phosphocreatine; Rats; Rats, Sprague-Dawley; Thioctic Acid

Although information on energy metabolism during hypoxemic-ischemic states is abundant, data on perinatal asphyxia (PA) are limited. As results from hypoxia-ischemia cannot be directly extrapolated to PA, a clinical entity characterized by acidosis, hypoxemia and hypercapnia, we decided to use a rat model of graded PA during delivery. Cesarean section was performed at the 21st day of gestation and the pups, still in the uterus horns, were asphyxiated from 0 to 20 minutes. In this model survival decreases with the length of asphyxia. Early changes of energy-rich phosphates in brain, heart and kidney were determined by HPLC. ATP and phosphocreatine gradually decreased with the length of asphyxia, with highest ATP depletion rate occurring in the kidney. ATP: brain 1.39 +/- 0.71 (0 min) to 0.06 microM/g wwt (20 min); heart 4.73 +/- 0.34 (0 min) to 1.08 +/- 0.47 (20 min); kidney 1.62 +/- 0.11 (0 min) to 0.02 +/- 0.02 (20 min). Phosphocreatine: brain 1.65 +/- 0.68 (0 min) to 0.51 +/- 0.45 microM/g (20 min); heart 6.98 +/- 0.38 (0 min) to 6.17 +/- 1.07 (20 min); kidney 8.23 +/- 0.86 (0 min) to 3.76 +/- 0.54 (20 min). We present data on energy derangement in a rat model of PA, closely resembling the clinical situation, showing that energy depletion precedes cell damage and death.

Topics: Adenine Nucleotides; Animals; Animals, Newborn; Asphyxia; Blood Gas Analysis; Brain; Chromatography, High Pressure Liquid; Disease Models, Animal; Energy Metabolism; Female; Hydrogen-Ion Concentration; Kidney; Lactic Acid; Myocardium; Phosphocreatine; Pregnancy; Rats; Rats, Sprague-Dawley

The purpose of this study was to determine whether retrograde continuous normothermic blood cardioplegic perfusion provides better protection to ischemic areas of the left and right ventricles than does antegrade continuous normothermic blood cardioplegic perfusion. Localized phosphorus 31 magnetic resonance spectroscopy was used to monitor the changes in energy metabolism and intracellular pH in the ventricles of pig hearts.. Ten isolated pig hearts received 20 minutes of antegrade continuous normothermic blood cardioplegic perfusion for collection of control (baseline) data, followed by 60 minutes of either antegrade continuous normothermic blood cardioplegic perfusion (n = 5) or retrograde continuous normothermic blood cardioplegic perfusion (n = 5) with occlusion of the left anterior descending and the right coronary arteries. The hearts were then subjected to antegrade continuous normothermic blood cardioplegic perfusion for 20 minutes. The perfusion pressures were maintained between 80 and 100 mm Hg and between 38 and 43 mm Hg during antegrade and retrograde continuous normothermic blood cardioplegic perfusions, respectively. Intracellular pH and creatine phosphate, inorganic phosphate, and adenosine triphosphate levels were measured continuously in each ventricle by means of localized phosphorus 31 magnetic resonance spectroscopy with 2 surface coils.. Both antegrade and retrograde continuous normothermic blood cardioplegic perfusion resulted in a significant increase in inorganic phosphate level and decreases in creatine phosphate level, adenosine triphosphate level, and intracellular pH. No significant differences in these changes were observed between the two groups. The creatine phosphate and adenosine triphosphate levels were significantly lower in the right ventricle than in the left ventricle during retrograde continuous normothermic blood cardioplegic perfusion. On reperfusion, the inorganic phosphate level, creatine phosphate level, and intracellular pH recovered completely; however, no recovery in the adenosine triphosphate level was seen in the ventricles of either group.. Retrograde continuous normothermic blood cardioplegic perfusion does not provide better protection to ischemic areas of the ventricles than does antegrade continuous normothermic blood cardioplegic perfusion under our experimental conditions.

Topics: Adenosine Triphosphate; Animals; Blood; Cardioplegic Solutions; Chromatography, High Pressure Liquid; Creatine Kinase; Disease Models, Animal; Energy Metabolism; Female; Heart Arrest, Induced; Heart Ventricles; Hydrogen-Ion Concentration; Intracellular Fluid; Magnetic Resonance Spectroscopy; Male; Myocardial Ischemia; Phosphates; Phosphocreatine; Swine; Temperature

The protease inhibitor aprotinin has been reported to have an anti-ischemic effect on left-ventricular myocardium in patients undergoing cardiopulmonary bypass operation. To examine the anti-ischemic properties beside its antifibrinolytic and inhibitory action on the kallikrein-bradykinin system, we investigated this substance in buffer-perfused rat hearts.. 24 isolated isovolumically contracting rat hearts received a 10-minute infusion of either 10000 units aprotinin or pure saline followed by 30 minutes of no-flow global ischemia and 45 minutes of reperfusion. Hemodynamics, high-energy phosphates, and troponin T as molecular marker of cardiac injury were studied.. During 15 minutes of reperfusion steady state function was identical in both groups, with a recovery of the developed left-ventricular pressure to 81.9+/-1.5% after protease inhibition and 83.0+/-2.6% in the controls. Coronary flow, myocardial oxygen consumption, and contractile reserve after maximum Ca++ stimulation were also identical. High-energy phosphates were comparably reduced in both groups (adenine nucleotides: 3.1+/-0.3 micromol/g ww after aprotinin vs. controls 2.7+/-0.4 micromol/g ww and creatine phosphate: 6.5+/-0.9 micromol/g ww vs. controls 4.7+/-1.1 micromol/g ww). However, release of the cardiac specific marker troponin T was lower after ischemia at several measurements (p<0.05). The total release of troponin T was 44+/-10 ng in the aprotinin treated hearts vs. 90+/-17 ng in the postischemic control hearts (p<0.05).. The findings demonstrate that aprotinin in a moderate dose is effective in reducing postischemic troponin release in a non-blood perfused system. Measurement of myocardial high-energy phosphates after aprotinin use was performed for the first time and indicates that not a reduction in severity of direct myocardial ischemic intensity but a beneficial action on processes causing release of troponin is the mode of action of this effect.

Topics: Adenosine Triphosphate; Animals; Aprotinin; Disease Models, Animal; Male; Myocardial Contraction; Myocardial Ischemia; Myocardium; Oxygen Consumption; Perfusion; Phosphocreatine; Plasma; Rats; Rats, Wistar; Serine Proteinase Inhibitors; Troponin T; Ventricular Pressure

The present study was designed to examine the effects of inhibition of nitric oxide synthase on cerebral energy metabolism after hypoxia-ischemia in newborn piglets. Ten 1- to 3-d-old piglets received N(omega)-nitro-L-arginine (NNLA), an inhibitor of nitric oxide synthase (NNLA-hypoxia, n = 5), or normal saline (hypoxia, n = 5) 1 h before cerebral hypoxia-ischemia. After the infusion, hypoxia-ischemia was induced by bilateral occlusion of the carotid arteries and decreasing FiO2 to 0.07 and maintained for 60 min. Thereafter, animals were resuscitated and ventilated for another 3 h. Using 1H- and 31P-magnetic resonance spectroscopy, cerebral energy metabolism was measured in vivo at 15-min intervals throughout the experiment. Phosphocreatine to inorganic phosphate ratios decreased from 2.74 +/- 0.14 to 0.74 +/- 0.36 (hypoxia group) and 2.32 +/- 0.17 to 0.18 +/- 0.10 (NNLA-hypoxia group) during hypoxia-ischemia. Thereafter, phosphocreatine to inorganic phosphate ratios returned rapidly to baseline values in the hypoxia group, but remained below baseline values in the NNLA-hypoxia group. Intracellular pH decreased during hypoxia-ischemia and returned to baseline values on reperfusion in both groups. Intracellular pH values were lower in the NNLA-hypoxia group (p < 0.001, ANOVA). Lactate was not present during the baseline period. After hypoxia-ischemia, lactate to N-acetylaspartate ratios increased to 1.34 +/- 0.28 (hypoxia group) and 2.22 +/- 0.46 (NNLA-hypoxia group). Lactate had disappeared after 3 h of reperfusion in the hypoxia group, whereas lactate to N-acetylaspartate ratios were 1.37 +/- 1.37 in the NNLA-hypoxia group. ANOVA demonstrated a significant effect of NNLA on lactate to N-acetylaspartate ratios (p < 0.001). Inhibition of nitric oxide synthase by NNLA tended to compromise cerebral energy status during and after cerebral hypoxia-ischemia in newborn piglets.

Topics: Animals; Animals, Newborn; Brain; Brain Ischemia; Cerebrovascular Circulation; Disease Models, Animal; Energy Metabolism; Enzyme Inhibitors; Hydrogen-Ion Concentration; Hypoxia, Brain; Lactic Acid; Magnetic Resonance Spectroscopy; Nitric Oxide Synthase; Nitroarginine; Phosphates; Phosphocreatine; Swine

Despite recent advances in the treatment, severe chronic heart failure (CHF) remains a syndrome associated with high mortality. Therefore, the search for new agents to improve both patient symptoms and survival, as well as the pursuit for detailed knowledge about pathophysiology of the failing heart, will continue to depend on relevant animal models. Large acute myocardial infarction (MI) initiates complex changes in the geometrical, structural, and biochemical architecture of both infarcted and non-infarcted regions of ventricular myocardium, which can profoundly affect left ventricular function and prognosis. In this paper we present a new model for non-invasive cardiac (31)P MRS in the rat. Volume-selective (31)P magnetic resonance spectroscopy and echocardiography were used for evaluation of myocardial energy metabolism, cardiac morphology and function in rats 3 days and 3 weeks after induction of large MI. The phosphocreatine:adenosine triphosphate (PCr:ATP) ratio was decreased in rats with MI comparing with controls both at 3 days (1.6+/-0.06 vs 2.7+/-0.04; mean+/-s.e.m. P<0.0001) and 3 weeks (1.6+/-0.07 v 2.7+/-0.02 P<0.0001) postinfarct. The results from the study demonstrate that postinfarct cardiac remodeling is a rapid process of changes not only in cardiac geometry, structure and function but also in myocardial energy metabolism after large transmural MI in the rat.

Topics: Adenosine Triphosphate; Animals; Diastole; Disease Models, Animal; Echocardiography; Energy Metabolism; Heart Rate; Heart Ventricles; Hemodynamics; Magnetic Resonance Spectroscopy; Male; Myocardial Infarction; Myocardium; Phosphocreatine; Rats; Rats, Sprague-Dawley; Systole; Ventricular Function, Left

The failing myocardium is characterized by depletion of phosphocreatine and of total creatine content. We hypothesized that this is due to loss of creatine transporter protein.. Creatine transporter protein was quantified in nonfailing and failing human myocardium (explanted hearts with dilated cardiomyopathy [DCM; n=8] and healthy donor hearts [n=8]) as well as in experimental heart failure (residual intact left ventricular tissue, rats 2 months after left anterior descending coronary artery ligation [MI; n=8] or sham operation [sham; n=6]) by Western blotting. Total creatine content was determined by high-performance liquid chromatography. Donor and DCM hearts had total creatine contents of 136.4+/-6.1 and 68.7+/-4.6 nmol/mg protein, respectively (*P<0.05); creatine transporter protein was 25.4+/-2.2 optical density units in donor and 17.7+/-2.5 in DCM (*P<0.05). Total creatine was 87.5+/-4.2 nmol/mg protein in sham and 65.7+/-4.2 in MI rats (*P<0.05); creatine transporter protein was 139.0+/-8.7 optical density units in sham and 82.1+/-4.0 in MI (*P<0.05).. Both in human and in experimental heart failure, creatine transporter protein content is reduced. This mechanism may contribute to the depletion of creatine compounds and thus to the reduced energy reserve in failing myocardium. This finding may have therapeutic implications, suggesting a search for treatment strategies targeted toward creatine transport.

Topics: Animals; Cardiomyopathy, Dilated; Carrier Proteins; Case-Control Studies; Creatine; Disease Models, Animal; Down-Regulation; Humans; Ion Transport; Membrane Transport Proteins; Middle Aged; Myocardial Contraction; Myocardial Infarction; Myocardium; Phosphocreatine; Rats; Rats, Wistar

Recovery of cardiac function and high-energy phosphates following ischemia and reperfusion were determined for hearts perfused with low potassium University of Wisconsin solution, high potassium University of Wisconsin solution, St Thomas' solution, or subjected to hypothermia alone. Isolated hearts were arrested for either 3 h at 15 degrees C or 6 h at 20 degrees C (n = 7 for each group) with one of the four solutions and then reperfused. Aortic flow after ischemic arrest at 20 degrees C was 40.3 +/- 13.3%, 79.3 +/- 10.0%, 64.3 +/- 11.9% and 43.9 +/- 15.9% of control values for high potassium University of Wisconsin solution, low potassium University of Wisconsin solution, St Thomas' solution and hypothermia alone, respectively. Similar results were observed in hearts subjected to ischemic arrest at 15 degrees C. Myocardial adenosine triphosphate and creatine phosphate after reperfusion tended to be higher in the low potassium University of Wisconsin solution group. It is concluded that low potassium University of Wisconsin solution may provide reliable cardioplegia during surgery that requires prolonged cardiac arrest in neonates and infants.

Topics: Adenosine; Adenosine Triphosphate; Allopurinol; Animals; Animals, Newborn; Bicarbonates; Calcium Chloride; Cardioplegic Solutions; Disease Models, Animal; Dose-Response Relationship, Drug; Glutathione; Heart; Heart Arrest; Heart Arrest, Induced; Hemodynamics; Hypothermia, Induced; In Vitro Techniques; Insulin; Magnesium; Organ Preservation Solutions; Phosphocreatine; Potassium; Potassium Chloride; Rabbits; Raffinose; Sodium Chloride

Putative cardioprotective action of flavone (10, 20 and 30 mg/kg) was investigated in a canine model of regional ischemia (20 min) followed by 60 min of reperfusion. In animals pretreated with vehicle, myocardial stunning was evidenced by significant changes in hemodynamic parameters (depressed mean arterial pressure, LV peak (+) dP/dt, LV peak (-) dP/dt and elevated LV end-diastolic pressure) and biochemical parameters (decreased myocardial ATP and rise in plasma malondialdehyde or MDA; a marker of free radical-induced injury). A reduction in plasma MDA was noted with 20 and 30 mg/kg flavone, although attenuation of myocardial dysfunction was evident with all the three doses. The results suggest that besides a significant dose-dependent antioxidant effect, flavone may also have some cardioprotective actions per se, which needs to be further investigated.

Topics: Adenosine Triphosphate; Animals; Cardiotonic Agents; Disease Models, Animal; Dogs; Flavones; Flavonoids; Hemodynamics; Myocardial Stunning; Phosphocreatine

Although cardioplegic protection of the hypertrophied heart remains a clinical challenge, we have previously observed enhanced recovery in rat hearts with pressure-overload hypertrophy induced by aortic banding. We investigated whether this unexpected result is found in other models of hypertrophy.. Hearts with hypertrophy induced by aortic banding or administration of desoxycorticosterone acetate were each compared with age-matched sham-operated and nonoperated controls. Spontaneously hypertensive rats and Wistar-Kyoto controls were also compared. We evaluated left ventricular isomyosin distribution by gel electrophoresis and recovery of isolated working rat hearts arrested at 8 degrees C for 2 hours.. The percentage of V3 isomyosin in hearts with hypertrophy from aortic banding or administration of desoxycorticosterone acetate was increased compared with the control groups. Recovery of aortic flow in all three groups of hypertrophied hearts was at least as good or better than their respective controls. There were no significant differences in ATP or glycogen between hypertrophied and control hearts before or after arrest.. Enhanced recovery of hypertrophied hearts is not specific to a single model. This level of recovery may be supported by induction of a "fetal genetic program," exemplified in the rat by the shift in isomyosin from predominantly V1 to the more efficient V3 isoform, which occurs in pressure-overloaded hearts.

Topics: Adenosine Triphosphate; Animals; Aorta, Abdominal; Cardioplegic Solutions; Chromatography, High Pressure Liquid; Desoxycorticosterone; Disease Models, Animal; Electrophoresis, Polyacrylamide Gel; Glycogen; Heart; Heart Arrest, Induced; Hemodynamics; Hypertrophy, Left Ventricular; In Vitro Techniques; Ligation; Myocardium; Myosins; Nephrectomy; Phosphocreatine; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Rats, Sprague-Dawley

31P-NMR was used to monitor myocardial bioenergetics in compensated and failing SHHF/MCC-fa(cp) (SHF) rat hearts. The SHHF/Mcc-fa(cp) (spontaneous hypertension and heart failure) rat is a relatively new genetic model in which all individuals spontaneously develop congestive heart failure, most during the second year of life. Failing SHF rat hearts displayed a pronounced decrease in resting PCr:ATP ratios (P<0.001), which was explained by a significant (P<0. 0001) drop in total creatine (47.2+/-3.1 nmol/mg protein) v age matched controls (106+/-3 nmol/mg protein). In end stage failure, NMR determined PCr was 2.9+/-0.1 micro mol/g wet weight under basal conditions. In contrast, 6- and 20-month-old controls and compensated SHFs had PCr values of 5.3+/-0.1, and 5.1+/-0.5 and 5. 1+/-0.2 micro mol/g wet weight. Both compensated and failing SHF hearts were metabolically compromised when the rate pressure product (RPP) was increased, as evidenced by an increase in Pi and a drop in PCr. Compensated SHF hearts, however, were able to increase rate pressure products (RRP, mmHg X beats/min) from 44.5+/-1.4 to 66.6+/-3. 4 K with dobutamine infusion, whereas hearts in end-stage failure were able to increase their RPP from baseline values of 27+/-4 K to only 37+/-7 K. The data indicate that a pronounced decline in PCr and total creatine signals the transition from compensatory hypertrophy to decompensation and failure in the SHF rat model of hypertensive cardiomyopathy.

Topics: Adenine Nucleotides; Adenosine Triphosphate; Animals; Creatine; Disease Models, Animal; Energy Metabolism; Heart Failure; In Vitro Techniques; Magnetic Resonance Spectroscopy; Male; Myocardium; Perfusion; Phosphocreatine; Phosphorus Isotopes; Rats; Rats, Inbred F344; Rats, Mutant Strains; Rats, Sprague-Dawley; Ventricular Dysfunction, Left

The cell volume is regulated not only by inorganic ions, but also by organic osmolytes, such as amino acids, methylamines, and polyhydric alcohols (polyols). Using proton nuclear magnetic resonance spectroscopy (1H-NMR), we measured the tissue concentrations of amino acids (alanine, aspartate, gamma-aminobutyric acid (GABA), glutamate, glutamine, N-acetyl-aspartate (NAA), taurine), methylamines (glycerophosphorylcholine (GPC), creatine+phosphocreatine (total creatine, tCr)), and polyols (myo-inositol) in the rat brain after middle cerebral artery occlusion (incomplete focal ischemia) or after decapitation (complete global ischemia). The total osmolytes expressed as a sum of total amino acids, total methylamines, and total polyols were significantly decreased at 24 h of focal ischemia (58.7% of control value, P=0.0025) whereas they were not changed following decapitation. The water content was increased from control value of 77.9%-84.1% after focal ischemia (P<0.0001) but not after decapitation. These results suggest that the brain organic osmolytes are involved in the process of edema formation following focal cerebral ischemia. Further elucidation of the cellular mechanisms regulating these organic osmolytes in cerebral ischemia may promote greater understanding of the pathophysiology involved in the evolution of brain edema.

Topics: Alanine; Amino Acids; Animals; Aspartic Acid; Brain Chemistry; Brain Ischemia; Creatine; Disease Models, Animal; gamma-Aminobutyric Acid; Glutamic Acid; Glutamine; Glycerylphosphorylcholine; Magnetic Resonance Spectroscopy; Male; Methylamines; Phosphocreatine; Rats; Rats, Sprague-Dawley; Taurine

The authors previously demonstrated, in a large-animal intracerebral hemorrhage (ICH) model, that markedly edematous ("translucent") white matter regions (> 10% increases in water contents) containing high levels of clot-derived plasma proteins rapidly develop adjacent to hematomas. The goal of the present study was to determine the concentrations of high-energy phosphate, carbohydrate substrate, and lactate in these and other perihematomal white and gray matter regions during the early hours following experimental ICH.. The authors infused autologous blood (1.7 ml) into frontal lobe white matter in a physiologically controlled model in pigs (weighing approximately 7 kg each) and froze their brains in situ at 1, 3, 5, or 8 hours postinfusion. Adenosine triphosphate (ATP), phosphocreatine (PCr), glycogen, glucose, lactate, and water contents were then measured in white and gray matter located ipsi- and contralateral to the hematomas, and metabolite concentrations in edematous brain regions were corrected for dilution. In markedly edematous white matter, glycogen and glucose concentrations increased two- to fivefold compared with control during 8 hours postinfusion. Similarly, PCr levels increased several-fold by 5 hours, whereas, except for a moderate decrease at 1 hour, ATP remained unchanged. Lactate was markedly increased (approximately 20 micromol/g) at all times. In gyral gray matter overlying the hematoma, water contents and glycogen levels were significantly increased at 5 and 8 hours, whereas lactate levels were increased two- to fourfold at all times.. These results, which demonstrate normal to increased high-energy phosphate and carbohydrate substrate concentrations in edematous perihematomal regions during the early hours following ICH, are qualitatively similar to findings in other brain injury models in which a reduction in metabolic rate develops. Because an energy deficit is not present, lactate accumulation in edematous white matter is not caused by stimulated anaerobic glycolysis. Instead, because glutamate concentrations in the blood entering the brain's extracellular space during ICH are several-fold higher than normal levels, the authors speculate, on the basis of work reported by Pellerin and Magistretti, that glutamate uptake by astrocytes leads to enhanced aerobic glycolysis and lactate is generated at a rate that exceeds utilization.

Topics: Adenosine Triphosphate; Aerobiosis; Animals; Astrocytes; Blood Proteins; Body Water; Brain Edema; Brain Injuries; Cerebral Hemorrhage; Disease Models, Animal; Energy Metabolism; Extracellular Space; Frontal Lobe; Glucose; Glutamates; Glycogen; Glycolysis; Hematoma; Lactates; Phosphocreatine; Swine; Time Factors

We investigated the changes in urinary bladder microvascular blood perfusion and energy metabolism following outlet obstruction and after relieving the obstruction. We induced mild bladder outlet obstruction in male New Zealand White rabbits. Following 2 weeks of obstruction, one group of animals (n = 6) was sacrificed, while outlet obstruction was relieved in three additional groups, which were sacrificed 1 (n = 5), 2 (n = 5) and 4 (n = 5) weeks after relieving the obstruction. Seven sham-operated rabbits served as controls. Before obstruction, immediately before relieving the obstruction and preceding the sacrifice, the microvascular blood perfusion of the urinary bladder was measured using a laser Doppler blood flowmeter. The detrusor content of phosphocreatine and adenine nucleotides was determined by high-performance liquid chromatography. The results showed: (1) 2 weeks of outlet obstruction significantly decreased the bladder microvascular blood perfusion, which recovered gradually after relief of the obstruction and returned to the control level by 4 weeks of obstruction reversal; (2) outlet obstruction reduced detrusor energy charge and phosphocreatine content, which were restored in parallel after relieving the obstruction; by 4 weeks the bladder had regained their normal energy producing capability; (3) bladder microvascular perfusion has a very close correlation with detrusor energy charge (r = 0.791, p < 0.001). In conclusion, our findings of the close correlation between microvascular perfusion and energy production in bladder outlet obstruction suggest an important role for the decreased microvascular blood perfusion in reducing bladder energy production.

Topics: Adenine Nucleotides; Analysis of Variance; Animals; Disease Models, Animal; Energy Metabolism; Laser-Doppler Flowmetry; Male; Microcirculation; Organ Size; Perfusion; Phosphocreatine; Rabbits; Reference Values; Regional Blood Flow; Urinary Bladder; Urinary Bladder Neck Obstruction

Proton magnetic resonance spectroscopy (1H-MRS) was used to measure the in vivo signal of N-acetylaspartate (NAA), a putative neuronal marker, in the brain of the mutant wobbler mouse, a model of motor neuron disease. The ratio of NAA to creatine-phosphocreatine, an internal standard, was significantly lower in five affected wobbler mice (0.79+/-0.05; mean+/-s.d.) than in five unaffected littermates (0.98+/-0.10, p = 0.006). Ubiquitin and phosphorylated heavy neurofilament immunoreactivities were increased in cortical neurons of affected animals. This is the first demonstration of cerebral neuronal pathology in the wobbler mouse, supporting its use as a model of amyotrophic lateral sclerosis. In vivo IH-MRS and correlative postmortem study of wobbler mouse brain will allow temporal monitoring of neuronal degeneration and responsiveness to neuroprotective pharmacotherapies.

Topics: Amyotrophic Lateral Sclerosis; Animals; Aspartic Acid; Axons; Caudate Nucleus; Creatine; Disease Models, Animal; Hippocampus; Immunohistochemistry; Magnetic Resonance Imaging; Mice; Mice, Neurologic Mutants; Motor Neuron Disease; Neocortex; Neurofilament Proteins; Neurons; Phosphocreatine; Putamen; Thalamus; Ubiquitins

To analyze metabolic changes associated with a fulminant malignant hyperthermia (MH) crisis developed spontaneously in an MH susceptible pig which was part of 12 pigs undergoing metabolic investigation (six MH susceptible and six controls) and had been anaesthetized with a non-triggering agent (pentobarbitone).. The pig was placed in a cradle and then inserted into a 4.7 T magnet bore. The semi-membranous muscle was submitted to three repetitive stimulation-recovery sessions. 31-P magnetic resonance spectra and mechanical data were recorded.. The pig developed a non-rigid MH crisis during recovery from the second set of experiments. Although no mechanical work was performed, dramatic metabolic changes were noted. Twitch tension decreased progressively reaching zero while mouth temperature continuously increased to 44.5 degrees C. Phosphocreatine (PCr) consumption was coupled to Pi accumulation. Also, a marked intracellular acidosis and a large accumulation of phosphomonoesters (PME) were observed, probably as a result of massive glycolysis activation. Interestingly, ATP level remained constant.. These irreversible mechanisms may constitute a metabolic dead-end coupling calcium pumping ATP-consuming processes and ATP synthesis through PCr breakdown and anaerobic glycolysis. They do not differ from metabolic changes previously reported in rigid forms of MH crisis.

Topics: Acidosis; Adenosine Triphosphate; Adjuvants, Anesthesia; Animals; Body Temperature; Calcium-Transporting ATPases; Disease Models, Animal; Glycolysis; Male; Malignant Hyperthermia; Muscle Fatigue; Muscle, Skeletal; Pentobarbital; Phosphocreatine; Swine

The effects of iloprost infusion (100 ng/kg/min for 75 min) alone and in combination with aspirin (3 mg/kg IV bolus) were compared in a canine model of myocardial reperfusion injury. Regional ischemia of 40 min was produced by temporary occlusion of the left anterior descending coronary artery, after which the myocardium was reperfused for a period of 3 hours. Mean arterial pressure (MAP), heart rate (HR), left ventricular end diastolic pressure (LVEDP), positive (+) LVdP/dtmax and negative (-) LVdP/dtmax were monitored. Rate pressure product and (-) dP/dt/Pmax were also derived from the above. Myocardial tissue levels of adenosine triphosphate (ATP), creatine phosphate (CP), glycogen and lactate were estimated. Following reperfusion in the saline treated group, there was a significant fall in (i) MAP, (ii) (+) LVdP/dtmax and (iii) (-) LVdP/dtmax. LVEDP was corrected about 2 hours after reperfusion. Despite correction of lactate accumulation, ATP and glycogen were not restored although the CP store was replenished. The hemodynamic profiles in both iloprost and in combination treated groups were similar; (i) depressed MAP (particularly during iloprost infusion) without any significant change in HR (ii) no significant depression in (+) LVdP/dtmax (iii) depression in (-) LVdP/dtmax but not when corrected for lower Pmax and (iv) a significant reduction in the incidence of reperfusion arrhythmias. Similarly, in both the drug/s treated groups, ATP, CP and lactate were normalised although glycogen store was not restored. The results of this study indicate (i) cardioprotective effect of iloprost even when administered prior to reperfusion and (ii) no additional protective effect of combining iloprost and aspirin.

Topics: Adenosine Triphosphate; Animals; Arrhythmias, Cardiac; Aspirin; Blood Pressure; Cyclooxygenase Inhibitors; Disease Models, Animal; Dogs; Drug Synergism; Drug Therapy, Combination; Glycogen; Heart Rate; Iloprost; Lactic Acid; Myocardial Reperfusion Injury; Myocardium; Phosphocreatine; Ventricular Pressure

We have developed a closed chest animal model that allows noninvasive monitoring of cardiac high energy phosphate metabolism before, during, and for at least 3 weeks after a myocardial infarction. Ten beagles underwent 2 h of coronary occlusion followed by 3 weeks of reperfusion. Myocardial high energy phosphates from 12-ml voxels were noninvasively tracked using 31P two-dimensional chemical shift imaging. Gadolinium enhanced 1H MRI identified the zone at risk, and radioactive microspheres assessed regional blood flow and partition coefficients. Occlusion of the left anterior descending coronary artery produced infarcts that were 13.7+/-8.8% (mean+/-SD) of the left ventricular volume. Rapid changes in the phosphocreatine and inorganic phosphate levels were observed during occlusion, whereas adenosine triphosphate levels decreased more slowly. All metabolites recovered to base-line levels 2 weeks after occluder release. Multiple inorganic phosphate peaks in the infarct voxel spectra indicated that more than one metabolically compromised tissue zone developed during occlusion and reperfusion. Microsphere data indicating three distinct blood flow zones during ischemia and reperfusion (<0.3, 0.3-0.75, and >0.75 ml/min/g) supported the grouping of pH values into three distinct metabolic distributions.

Topics: Adenosine Triphosphate; Animals; Blood Flow Velocity; Contrast Media; Disease Models, Animal; Dogs; Female; Follow-Up Studies; Gadolinium DTPA; Hydrogen-Ion Concentration; Image Enhancement; Image Processing, Computer-Assisted; Magnetic Resonance Spectroscopy; Microspheres; Myocardial Infarction; Myocardial Reperfusion; Phosphocreatine; Phosphorus Isotopes

To clarify the action of dibutyryl cyclic adenosine monophosphate (DBcAMP) on reperfused ischemic muscle, experiments were conducted using the hindlimbs of 18 male Lewis rats. At the midportion of the thigh all tissues except for the femoral artery and vein were transected, and a route for continuous intravenous infusion was secured in a contralateral limb vein. After inducing total ischemia by clamping the femoral artery and vein with a vascular clamp for 4 h, the limb was reperfused for 1 h. Blood flow was then compared using the hydrogen gas clearance method in a group in which DBcAMP 10 mg was continuously infused from a vein in the contralateral hindlimb from 1 h prior to the induction of ischemia to 1 h after the completion of ischemia (DBcAMP group), a group in which saline was infused in the same manner (control group), and a group which was subjected to biopsy alone (biopsy group). The percent change in blood flow was significantly higher in the DBcAMP group than in the control group at 15 and 30 min after the release of the clamp. Adenosine triphosphate (ATP), phosphocreatine (PCr), and lipid peroxide (LPO) were measured in tissue samples obtained 1 h after reperfusion. Serum LPO was measured in blood samples collected at the same time. ATP values were higher in the DBcAMP group than in the control group. PCr was significantly higher in the DBcAMP group than in the control group. LPO levels in skeletal muscle tissue did not differ significantly between the DBcAMP and control groups. In contrast, serum LPO levels were significantly lower in the DBcAMP group than the control group. On morphologic analysis the control and DBcAMP groups showed normal vascular endothelial cells and absence of the 'no-reflow' phenomenon. These data confirm that in this reperfusion model the administration of DBcAMP enhances the viability of skeletal muscle cells. Moreover, mediated by an effect on vascular endothelial cells this agent is thought to be of help in mitigating the vascular endothelial cell injury occurring in acute ischemic injury. DBcAMP may be a useful agent in mitigating skeletal muscle ischemia-reperfusion injury.

Topics: Adenine Nucleotides; Animals; Blood Flow Velocity; Bucladesine; Disease Models, Animal; Endothelium, Vascular; Lipid Peroxides; Male; Microscopy, Electron; Muscle, Skeletal; Phosphocreatine; Rats; Rats, Inbred Lew; Reperfusion Injury

The effect of insulin induced hypoglycemia on cerebral energy metabolism was examined in four newborn piglets. Cerebral energy metabolism was assessed using in vivo 31P-nuclear magnetic resonance spectroscopy. It was demonstrated that the normal level of phosphocreatine/inorganic phosphate (PCr/Pi), an indicator of phosphorylation potential, was maintained at a blood glucose level of 40 mg/dL or above, whereas when blood glucose was reduced to less than 40 mg/dL, PCr/Pi rapidly decreased in parallel with this. Below the critical blood glucose level of 40 mg/dL, a positive correlation (y = 0.02x + 0.632; r = 0.668; P < 0.001) existed between blood glucose and PCr/Pi. In the present investigation, a reduction of blood glucose level to 20 mg/dL or lower resulted in a PCr/Pi of less than 1, indicating a state of cerebral energy failure. The intracellular pH (pHi) was 7.08 +/- 0.05 at the onset and 7.15 +/- 0.07 in the hypoglycemic state, indicating no significant difference between the two groups. The present study has clarified that cerebral energy failure occurs when the blood glucose level is about 20 mg/dL or lower. The critical point of blood glucose exists to maintain brain energy metabolism.

Topics: Animals; Animals, Newborn; Brain; Disease Models, Animal; Energy Metabolism; Hypoglycemia; Insulin; Magnetic Resonance Spectroscopy; Phosphocreatine; Phosphorus Radioisotopes; Swine

We studied peripheral skeletal muscle metabolism in monocrotaline-treated rats. Two distinct groups emerged: a percentage of the animals developed ventricular hypertrophy, with no signs of heart failure (compensated group), whilst others, besides ventricular hypertrophy, developed the syndrome of congestive heart failure (CFH group). Oxidative metabolism and redox cellular state were expressed in terms of creatine phosphate, purine (ATP, ADP and AMP) and pyridine (NAD and NADH) nucleotides tissue content. Skeletal muscles with different metabolism were studied: (a) Soleus (oxidative), (b) extensor digitorium longus (glycolytic) and tibialis anterior (oxidative and glycolytic). The results showed that in CFH animals a decreased high-energy phosphates content occurs in the soleus and extensor digitorum longus, but not in the tibialis anterior. In the soleus. ATP declined from 20.31 +/- 2.5 of control group to 9.55 +/- 0.61 mumol/g dry wt. while in the extensor digitorum longus ATP declined from 30.92 +/- 2.68 to 22.7 +/- 1.54 mumol/g dry wt. In both these muscles, a shift of NAD/NADH couple towards oxidation was also observed (from 26.58 +/- 3.34 to 6.95 +/- 0.97 and from 18.88 +/- 3.43 to 10.57 +/- 1.61, respectively). These alterations were more evident in the aerobic soleus muscle. On the contrary, no major changes occurred in skeletal muscle metabolism of compensated animals. The results show that: (1) a decrease in muscle high-energy phosphates occurs in CFH; (2) this is accompanied by a decrease of NAD/NADH couple suggesting an impairment in oxygen utilization or availability.

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Cardiomegaly; Disease Models, Animal; Female; Heart Failure; Monocrotaline; Muscle, Skeletal; NAD; Organ Size; Oxidation-Reduction; Phosphocreatine; Rats; Rats, Sprague-Dawley

The most serious consequence of heart failure is the shortened life expectancy, which may be associated with myocardial energy starvation.. Eight-week-old male Sprague-Dawley rats received 6 intraperitoneal injections of adriamycin (group A: total dose; 15 mg/kg body weight) or vehicle (group C) over 2 weeks. Rats then received either 272 mg/kg daily of oral 1-carnitine (A-LC and C-LC groups) or saline (A-S and C-S groups) for 6 weeks. The cumulative mortality rate in the A-LC group was significantly lower than in the A-S group (13 vs 42%, P = .028). Myocardial levels of high-energy phosphate compounds (ATP and creatine phosphate) and fatty acid metabolites (free carnitine, short-chain and long-chain acylcarnitine, and long-chain acyl CoA) in the left ventricle were measured the day after the last dose of drug or vehicle was administered. ATP was decreased by 73%, creatine phosphate by 61%, free carnitine by 52%, short-chain acylcarnitine by 48%, and long-chain acylcarnitine by 56% in the A-S group compared to the C-S group. Long-chain CoA was increased by 168% in the A-S group. Levels of myocardial high-energy phosphate compounds and fatty acid metabolites were near normal in adriamycin- and 1-carnitine-treated rats.. Preservation of the myocardial level of carnitine by 1-carnitine treatment prolonged survival of rats with adriamycin-induced failure by improving the myocardial metabolism of fatty acids.

Topics: Acyl Coenzyme A; Adenosine Triphosphate; Administration, Oral; Analysis of Variance; Animals; Carnitine; Culture Techniques; Disease Models, Animal; Doxorubicin; Drug Administration Schedule; Heart Failure; Male; Myocardium; Phosphocreatine; Rats; Rats, Sprague-Dawley; Survival Rate

We wished to determine whether histidine scavenges hydroxyl radical, H2O2, and superoxide anion in vitro and to investigate the protective effect of histidine on isolated perfused rat hearts after global ischemia (40 min) and reperfusion (30 min) (I/R). Left ventricular (LV) function was recorded and coronary effluent was collected for measurement of lactate dehydrogenase (LDH) before ischemia and at 5, 10, 15, and 30 min of reperfusion. At the end of the experiment, a portion of the LV wall was fixed with 2% glutaraldehyde for morphological analysis; the remaining heart was immediately frozen in liquid nitrogen for determination of adenine nucleotides. Histidine effectively quenched hydroxyl radicals and H2O2, but not superoxide anions, in in vitro and in vivo conditions. Hearts treated with histidine exhibited significantly greater functional recovery during reperfusion as compared with nontreated hearts (p < 0.05). Cell morphology was well preserved, and enzyme release was significantly attenuated by histidine treatment (p < 0.05). Histidine raised the ATP level to 73% and the creatine phosphate level to 68% of normal control during reperfusion. Total adenine nucleotide pool and energy charge rate in histidine-treated hearts significantly increased as compared with those in nontreated hearts (p < 0.05), but no effect on ATP and creatine phosphate was noted during ischemia, Histidine prevents postischemic reperfusion injury in isolated heart by inhibiting reactive O2 species and preserving high-energy phosphates (HEP).

Topics: Adenosine Triphosphate; Animals; Ascorbic Acid; Chromatography, High Pressure Liquid; Disease Models, Animal; Free Radical Scavengers; Gentisates; Glutaral; Heart Ventricles; Histidine; Hydrogen Peroxide; Hydroxybenzoates; Hydroxyl Radical; L-Lactate Dehydrogenase; Male; Myocardial Reperfusion Injury; Phosphates; Phosphocreatine; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Superoxides; Tissue Embedding; Ventricular Function, Left

Heart rate (HR) is a major factor determining the severity of myocardial ischemia, and HR reduction is an effective therapy for myocardial ischemia. We tested the effects of HR reduction induced by either UL-FS 49 or atenolol on regional myocardial blood flow, function, and infarct size (IS) in a porcine model of 90-min low-flow ischemia and 2-h reperfusion. In 24 Göttinger miniswine, the left anterior descending coronary artery (LAD) was cannulated and hypoperfused at constant inflow to reduce anterior systolic wall thickening (AWT, sonomicrometry) by approximately 85%. Eight swine served as a placebo group, and 8 other swine received UL-FS 49 (0.60 mg/kg intravenously, i.v.) after 10-min ischemia. In the remaining 8 swine, atenolol was infused after 10-min ischemia at a dosage [mean 1.75 +/- 1.20 (SD) mg/kg i.v.] to mimic the HR reduction observed with UL-FS 49. Systemic hemodynamics, subendocardial blood flow (ENDO, microspheres) and AWT were measured under control conditions, at 10 and 90 min of ischemia. In the swine receiving UL-FS 49 or atenolol, additional measurements were made 5 min after administration of the respective drug. After 2-h reperfusion, IS (percentage of area at risk) was determined with TTC-staining. Five minutes after administration of UL-FS 49, HR was decreased from 113 +/- 9 to 83 +/- 13 beats/min (p < 0.05) and remained unchanged when ischemia was prolonged to 90 min. In the swine receiving atenolol, HR was reduced from 117 +/- 14 to 93 +/- 7 beats/min (p < 0.05) 5 min after drug administration and decreased further to 87 +/- 10 beats/min when ischemia was prolonged to 90 min. After 10 min of ischemia, AWT in the placebo, UL-FS 49, and atenolol group was decreased to 7.0 +/- 5.5, 6.4 +/- 3.5, and 6.2 +/- 3.3% (all p < 0.05 vs. control), respectively. The reduction in ENDO was also comparable among the three groups. In the placebo group, AWT remained unchanged when ischemia was prolonged to 90 min (4.4 +/- 2.6%). In swine receiving atenolol, AWT tended to increase (13.6 +/- 10.5%), whereas in swine receiving UL-FS 49, AWT was significantly increased to 21.4 +/- 7.1% (p < 0.05 vs. 10-min ischemia and vs. the placebo and atenolol groups). IS was significantly reduced in swine receiving atenolol (3.9 +/- 3.5%) or UL-FS 49 (5.8 +/- 4.6%) as compared with the placebo-group (10.4 +/- 8.9%).(ABSTRACT TRUNCATED AT 400 WORDS)

Topics: Adenosine Triphosphate; Animals; Atenolol; Benzazepines; Blood Pressure; Bradycardia; Cardiovascular Agents; Coronary Circulation; Disease Models, Animal; Female; Heart; Heart Rate; Injections, Intravenous; Lactates; Male; Myocardial Infarction; Myocardial Ischemia; Myocardium; Oxygen Consumption; Phosphocreatine; Reperfusion Injury; Swine; Swine, Miniature

We investigated whether transient adenosine (Ado) infusion before ischemia had the same effect on myocardial metabolism and function as ischemic preconditioning (IP). The control (C) group underwent 15 min of coronary artery occlusion followed by 120 min of reperfusion. The Ado group received a 15-min infusion of Ado (200 micrograms.kg-1.min-1) into the left atrium starting 20 min before ischemia. IP was elicited by two cycles of 5-min ischemia and 5-min reperfusion. In the area at risk, tissue levels of ATP, creatine phosphate (CP), and intracellular pH (pHi) were serially measured by 31P-nuclear magnetic resonance spectroscopy in 10 pigs from each group, and percent segment shortening (%SS) was measured in 7 pigs from each group. ATP and pHi were preserved after 15 min of ischemia in both Ado and IP groups [ATP = 64 +/- 7, 76 +/- 6, and 74 +/- 9% of baseline; pHi = 6.35 +/- 0.19, 6.54 +/- 0.11, and 6.64 +/- 0.11 in C, Ado, and IP groups, respectively (P < 0.05, Ado and IP vs. C)]. During reperfusion, ATP was restored progressively in both groups [71 +/- 7, 90 +/- 8, and 91 +/- 9% of baseline at 120 min of reperfusion in C, Ado, and IP groups, respectively (P < 0.05, Ado and IP vs. C)]. However, in contrast to the IP group, CP was not preserved during 15-min ischemia nor did it show persistent overshoot during reperfusion in the Ado group. There were no significant differences in %SS during ischemia and reperfusion among the three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adenosine; Adenosine Triphosphate; Animals; Coronary Circulation; Disease Models, Animal; Energy Metabolism; Heart Atria; Hydrogen-Ion Concentration; Infusions, Parenteral; Intracellular Fluid; Magnetic Resonance Imaging; Myocardial Reperfusion Injury; Myocardium; Phosphocreatine; Swine

Limitation of myocardial injury and infarction has been demonstrated by interventions such as ischemic preconditioning or the use of pyruvate as a substrate, which reduces glycogen content before, and acidosis during, ischemia. An isolated perfused rat heart model of global ischemia was employed to test the hypothesis that glycogen depletion reduces ischemic injury as measured by creatine kinase release. 31P-nuclear magnetic resonance spectroscopy was used to measure high-energy phosphates (ATP and phosphocreatine), phosphomonoesters (PME), and intracellular pH. Compared with control glucose-perfused hearts with normal glycogen content (1.49 +/- 0.13 mg Glc/g wet wt), glycogen-depleted pyruvate, ischemic preconditioned, and glycogen-depleted glucose hearts all had reduced glycogen content before ischemia (0.62 +/- 0.16, 0.81 +/- 0.10, and 0.67 +/- 0.12 mg Glc/g wet wt, respectively; P = 0.003) and significantly higher pH at the end of ischemia (5.85 +/- 0.02, 6.33 +/- 0.06, 6.24 +/- 0.04, and 6.12 +/- 0.02 in control, glycogen-depleted pyruvate, preconditioned, and glycogen-depleted glucose-perfused hearts, respectively; P < 0.01), although acidification during the initial phase of ischemia was differentially affected by the three interventions. Glycogen-depleted pyruvate and preconditioned hearts had reduced PME accumulation, greater recovery of function and phosphocreatine, and lower creatine kinase release on reperfusion, whereas glycogen-depleted glucose-perfused hearts were similar to control hearts. In summary, glycogen depletion by these three methods limits the fall in pH during global ischemia, although glycogen depletion in the absence of preconditioning does not limit ischemic injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adenosine Triphosphate; Animals; Creatine Kinase; Disease Models, Animal; Glucose; Glycogen; Glycolysis; Hydrogen-Ion Concentration; In Vitro Techniques; Intracellular Fluid; Magnetic Resonance Spectroscopy; Male; Myocardial Ischemia; Perfusion; Phosphates; Phosphocreatine; Rats; Rats, Sprague-Dawley; Ventricular Function, Left

Quantitative 31P NMR was used to follow the time variation of the hypometabolic response to hypoxic partial ischemia in an animal model. The purpose of the study was to establish the value of this repeated spectroscopy operating by means of a surface coil. It aimed at determining whether a therapeutic intervention could influence the transient changes occurring during the insult or early recovery. A pharmacological substance was thus used during a reversible forebrain ischemia, induced by a combination of vascular occlusion and mild hypoxia in two groups of rats. As an available and convenient example, L-carnitine was chosen. Statistical analysis of the experimental results revealed a significant difference of the Pi and PCr levels between treated and untreated animals.

Topics: Adenosine Triphosphate; Animals; Basilar Artery; Carnitine; Carotid Arteries; Disease Models, Animal; Fatty Acids; Hydrogen-Ion Concentration; Hypoxia, Brain; Infusions, Intravenous; Ischemic Attack, Transient; Magnetic Resonance Spectroscopy; Male; Oxidation-Reduction; Phosphates; Phosphocreatine; Phosphorus Isotopes; Prosencephalon; Rats; Rats, Wistar; Reperfusion

Retrograde normothermic blood cardioplegia has been shown to provide myocardial protection during certain bypass procedures. However, a number of animal studies have shown less than optimal myocardial protection with this technique.. Isolated, beating porcine hearts were perfused antegradely (aortic root pressure = 75 to 95 mm Hg) for 30 minutes. Arrest was induced and maintained for 60 minutes with high K+ blood cardioplegia delivered either antegradely (n = 8) or retrogradely (n = 8) (coronary sinus pressure = 35 to 55 mm Hg). Perfusate was switched to normokalemic blood for recovery of sinus rhythm (30 minutes). Intracellular pH, creatine phosphate, inorganic phosphate, and adenosine triphosphate were monitored continuously and noninvasively with phosphorus 31 magnetic resonance spectroscopy throughout the experiment, and functional variables (rate-pressure product and the positive and negative first derivatives of left ventricular pressure) were assessed concurrently.. Antegrade cardioplegia maintained high-energy metabolites, intracellular pH, and myocardial function. Retrograde normothermic blood cardioplegia resulted in an increase in inorganic phosphate (197% +/- 15% of control) and a decrease in creatine phosphate (51% +/- 6% of control). There was no significant difference in myocardial function between the two groups (p > 0.05). The magnetic resonance spectroscopy data indicate ischemia occurred within 2 minutes of the initiation of retrograde perfusion.. This study suggests that retrograde normothermic blood cardioplegia causes a transition of the myocardium to ischemic metabolism in the normal porcine heart.

Topics: Adenosine Triphosphate; Animals; Disease Models, Animal; Female; Heart Arrest, Induced; Hemodynamics; Magnetic Resonance Spectroscopy; Male; Monitoring, Intraoperative; Myocardial Reperfusion Injury; Phosphates; Phosphocreatine; Phosphorus Isotopes; Swine; Time Factors

Alterations in energy metabolism, reduced fatty acid oxidation, and cardiac carnitine content have been implicated in the evolution from compensated to decompensated cardiac hypertrophy. We determined high-energy nucleotide levels in hypertrophied quiescent cardiomyocytes isolated from rat hearts 4 weeks after banding of abdominal aorta. In hypertrophied quiescent cardiomyocytes, a decrease in ATP content (p = 0.03), and ratios of ATP/total adenine nucleotides and of ATP/ADP were observed, together with an increase in ADP. In addition, palmitate, but not glucose oxidation, was markedly reduced in hypertrophied myocytes. In the presence of 25 microM propionyl-L-carnitine (PLC) or L-carnitine (LC), palmitate oxidation was significantly stimulated in hypertrophied myocytes. The ATP/ADP ratio was significantly increased only with PLC. This effect was not due to an enhanced PLC uptake, since total PLC uptake was 50% lower than that of LC. Changes in the energy generating system of quiescent myocytes occur early in pressure overload hypertrophy, and these alterations can be attenuated by PLC.

Topics: Adenosine Diphosphate; Adenosine Triphosphate; Animals; Cardiomegaly; Cardiotonic Agents; Carnitine; Cell Size; Disease Models, Animal; Energy Metabolism; Fatty Acids; Glucose; Heart; Heart Ventricles; In Vitro Techniques; Male; Myocardium; Oxidation-Reduction; Palmitates; Phosphocreatine; Rats; Rats, Inbred WKY

The authors studied the effects of hydrocephalus on the high-energy phosphate metabolism of the brain and the impact of ventriculoperitoneal (VP) shunting on these changes in an experimental model of hydrocephalus. High-energy phosphate metabolism was analyzed using in vivo magnetic resonance (MR) imaging and 31P MR spectroscopy. Hydrocephalus was produced in 34 1-week-old kittens by cisternal injection of 0.05 ml of a 25% kaolin solution. Sixteen litter mates were used as controls. A VP shunt with a distal slit valve was implanted in 17 of the 34 hydrocephalic animals 10 days after induction of hydrocephalus. Both MR imaging and 31P MR spectroscopy were obtained 1 and 3 weeks after either kaolin or distilled water injection. Untreated hydrocephalic animals had marked dilatation of the lateral ventricles and periventricular edema. Magnetic resonance spectroscopy showed a significant decrease in the energy index ratio of phosphocreatine (PCR): inorganic phosphate (PI) and an increase in the PI:adenosine triphosphate (ATP) ratio. There was a direct correlation between the decrease in the energy index and ventricular size. Compared with preoperative scans, shunted animals showed no periventricular edema, and the ventricles decreased in size. Also, PCR:PI and PI:ATP ratios were within the levels of controls. This study suggests that neonatal hydrocephalus results in a mild hypoxic/ischemic insult that is treatable by VP shunting.

Topics: Adenosine Triphosphate; Animals; Animals, Newborn; Cats; Disease Models, Animal; Hydrocephalus; Magnetic Resonance Spectroscopy; Phosphates; Phosphocreatine; Ventriculoperitoneal Shunt

We examined whether opening of the ATP-sensitive potassium (KATP) channels in the ischemic myocardium plays an important cardioprotective role during ischemia. Dogs were anesthetized with sodium pentobarbital (30 mg/kg, i.v.). Sixty minutes after treatment of the dog with glibenclamide (0.3 or 3 mg/kg, i.v.), the LAD was ligated. At 3 or 15 min after LAD ligation, left ventricular tissue was taken from the ischemic region to measure tissue metabolite levels. After ischemia, the tissue levels of ATP and creatine phosphate decreased to 49-74% and 26-34%, respectively, and lactate level increased to 380-660%. Ischemia (either 3 or 15 min) increased the levels of G6P and F6P and decreased the FDP level, indicating the inhibition of glycolysis. Glibenclamide at either dose decreased the level of blood glucose by 20-30% and increased the blood insulin level twice. The decrease in ATP and increase in lactate due to ischemia were significantly enhanced by glibenclamide at a dose of 3 mg/kg. The increase in G6P due to 15 min of ischemia were also enhanced significantly by 0.3 and 3 mg/kg of glibenclamide. Glibenclamide worsened the metabolic alterations produced by ischemia. These results suggest that KATP channels that can be inhibited by glibenclamide may perform some functions in the ischemic myocardium.

Topics: Adenosine Monophosphate; Adenosine Triphosphate; Animals; Blood Glucose; Blood Pressure; Disease Models, Animal; Dogs; Energy Metabolism; Female; Fructosephosphates; Glucose-6-Phosphate; Glucosephosphates; Glyburide; Heart; Heart Rate; Insulin; Male; Myocardial Ischemia; Myocardium; Phosphocreatine; Potassium Channels

The goal of this study was to introduce a new method inducing an experimental brain injury model using ESWL(Extracorporeal Shock Wave Lithotripsy) and to evaluate findings of localized lesions on 1H MR imaging and the response of cerebral energy metabolism using a 31P MR spectroscope to the ESWL brain injury in cats. This study also examined effects of cerebral protective drugs. 1) There were no statistically significant changes in pH at all measurement points. 2) In the trauma group, initial decrease of PCr/Pi was seen at 30 to 60 minutes with return to control levels by 2 hours after injury(P < 0.05), followed by a second decline at 4 hours which lasted until 8 hours after injury. 3) Significant recovery in PCr/Pi(P < 0.05) was observed in both the THAM and dexamethasone treated groups at all measurement points and in the mannitol treated group only temporary recovery at 30 and 60 minutes (P < 0.05). 4) High intensity signals were seen on 1H MR imaging in traumatized animals. This study demonstrated the immediate and persistent recovery of cerebral energy metabolism using THAM or dexamethasone and an immediate but transient effect with mannitol in traumatized animals.

Topics: Adenosine Triphosphate; Animals; Brain; Brain Injuries; Cats; Dexamethasone; Disease Models, Animal; Energy Metabolism; Hydrogen-Ion Concentration; Lithotripsy; Magnetic Resonance Spectroscopy; Phosphates; Phosphocreatine; Random Allocation; Tromethamine

The recently developed controlled cortical impact model of brain injury in rats may be an excellent tool by which to attempt to understand the neurochemical mechanisms mediating the pathophysiology of traumatic brain injury. In this study, rats were subjected to lateral controlled cortical impact brain injury of low grade severity; their brains were frozen in situ at various times after injury to measure regional levels of lactate, high energy phosphates, and norepinephrine. Tissue lactate concentration in the injury site left cortex was increased in injured animals by sixfold at 30 min and twofold at 2.5 h and 24 h after injury (p < 0.05). At all postinjury times, lactate concentration was also increased in injured animals by about twofold in the cortex and hippocampus adjacent to the injury site (p < 0.05). No significant changes occurred in the levels of ATP and phosphocreatine in most of the brain regions of injured animals. However, in the primary site of injury (left cortex), phosphocreatine concentration was decreased by 40% in injured animals at 30 min after injury (p < 0.05). The norepinephrine concentration was decreased in the injury site left cortex of injured animals by 38% at 30 min, 29% at 2.5 h, and 30% at 24 h after injury (p < 0.05). The level of norepinephrine was also reduced by approximately 20% in the cortex adjacent to the injury site in injured animals. The present results suggest that controlled cortical impact brain injury produces disorder in the neuronal oxidative and norepinephrine metabolism.

Topics: Adenosine Triphosphate; Animals; Brain Injuries; Cerebral Cortex; Disease Models, Animal; Freezing; Hippocampus; Lactates; Lactic Acid; Male; Norepinephrine; Phosphates; Phosphocreatine; Rats; Rats, Inbred F344; Tissue Distribution

The mechanism responsible for sepsis-induced myocardial depression is not known. To determine if sepsis-induced myocardial depression is caused by inadequate free energy available for work, we studied myocardial energy metabolism in a canine model of sepsis. Escherichia coli-infected (n = 18) or sterile (n = 16) fibrin clots were implanted intraperitoneally into beagles. Myocardial function and structure was assessed using radionuclide ventriculograms, echocardiograms, and light and electron microscopy. The adequacy of energy metabolism was evaluated by comparing catecholamine-induced work increases [myocardial O2 consumption (MVO2) and rate pressure product (RPP)] with a simultaneously obtained estimate of intracellular free energy [phosphocreatine-to-adenosine triphosphate ratio (PCr:ATP)] determined by 31P-magnetic resonance spectroscopy. When compared with control animals, septic animals had a decrease in left ventricular ejection fraction (EF, P < 0.0001) on day 1 and fractional shortening (FS, P < 0.0003) on day 2 after clot implantation. On day 2, neither septic nor control animals had statistically significant decreases in PCr:ATP, despite catecholamine-induced increases in MVO2 and RPP (mean maximal increases in septic animals 135 +/- 31 and 51 +/- 10%, respectively). Light and electron microscopic findings showed that hearts of septic animals, compared with control animals, had a greater degree of morphological abnormalities. Thus, in a canine model of sepsis with alterations in myocyte ultrastructure and documented myocardial depression (decreased EF and FS), intracellular free energy levels (PCr:ATP) were maintained despite catecholamine-induced increases in myocardial work (increased MVO2 and RPP), suggesting high-energy synthetic capabilities are not limiting cardiac function.

Topics: Adenosine Triphosphate; Animals; Bacteremia; Disease Models, Animal; Dogs; Endothelium, Vascular; Energy Metabolism; Epinephrine; Escherichia coli Infections; Heart; Mitochondria, Heart; Mitochondrial Swelling; Myocardium; Myofibrils; Oxygen Consumption; Phenylephrine; Phosphocreatine; Reference Values; Time Factors; Ventricular Function, Left

Spiraprilat, a new angiotensin-converting enzyme (ACE) inhibitor, was compared with enalaprilat for its ability to improve left ventricular (LV) function and metabolism in anesthetized open-chest dogs with a new model of acute LV failure (ALVF) induced by embolization of the left coronary artery with 50 microns plastic microspheres followed by intravenous (i.v.) infusion of methoxamine. With this procedure, LV end-diastolic pressure (LVEDP) increased from 4.2 +/- 0.7 to 12.8 +/- 1.3 mm Hg and remained at approximately 12 mm Hg throughout the experiment. Cardiac output (CO) decreased from 1.25 +/- 0.12 to 0.79 +/- 0.06 and 0.55 +/- 0.02 L/min at 30 and 90 min after methoxamine infusion, respectively. LVdP/dtmax and dP/dt/P decreased, while total peripheral resistance (TPR) increased. These hemodynamic changes indicated establishment of stable ALVF of a moderate degree. Moreover, decreases in myocardial lactate consumption and contents of creatine phosphate in the myocardium indicated the existence of moderate ischemia. The new ACE inhibitor, spiraprilat, as well as enalaprilat (30 micrograms/kg i.v.) effectively decreased mean aortic pressure (30%), LVEDP (20%), and TPR (30%) and increased stroke volume (SV) CO, and dP/dt/P. Both agents decreased myocardial oxygen consumption (20%) and caused a significant increase in myocardial creatine phosphate contents. These data indicate that the beneficial effects of both inhibitors extended not only to LV function but also to myocardial energy metabolism in ALVF.

Topics: Adenosine Triphosphate; Anesthesia; Angiotensin-Converting Enzyme Inhibitors; Animals; Blood Pressure; Coronary Vessels; Disease Models, Animal; Dogs; Enalapril; Heart Failure; Lactates; Lactic Acid; Methoxamine; Microspheres; Myocardium; Oxygen Consumption; Phosphocreatine; Vascular Resistance; Ventricular Function, Left

Cardiac function and energetics in experimental renal failure in the rat (5/6 nephrectomy) have been investigated by means of an isolated perfused working heart preparation and an isometric Langendorff preparation using 31P nuclear magnetic resonance (31P NMR). 4 wk after nephrectomy cardiac output of isolated hearts perfused with Krebs-Henseleit buffer was significantly lower (P < 0.0001) at all levels of preload and afterload in the renal failure groups than in the pair-fed sham operated control group. In control hearts, cardiac output increased with increases in perfusate calcium from 0.73 to 5.61 mmol/liter whereas uremic hearts failed in high calcium perfusate. Collection of 31P NMR spectra from hearts of renal failure and control animals during 30 min normoxic Langendorff perfusion showed that basal phosphocreatine was reduced by 32% to 4.7 mumol/g wet wt (P < 0.01) and the phosphocreatine to ATP ratio was reduced by 32% (P < 0.01) in uremic hearts. During low flow ischemia, there was a substantial decrease in phosphocreatine in the uremic hearts and an accompanying marked increase in release of inosine into the coronary effluent (14.9 vs 6.1 microM, P < 0.01). We conclude that cardiac function is impaired in experimental renal failure, in association with abnormal cardiac energetics and increased susceptibility to ischemic damage. Disordered myocardial calcium utilization may contribute to these derangements.

Topics: Adenosine Diphosphate; Adenosine Triphosphate; Animals; Blood Pressure; Cardiac Output; Coronary Circulation; Creatinine; Disease Models, Animal; Heart; Heart Rate; Hydrogen-Ion Concentration; In Vitro Techniques; Kidney Failure, Chronic; Magnetic Resonance Spectroscopy; Male; Multivariate Analysis; Myocardium; Nephrectomy; Phosphates; Phosphocreatine; Rats; Rats, Wistar; Reference Values; Urea

To evaluate the effects of standard-dose versus high-dose epinephrine on myocardial high-energy phosphate metabolism during resuscitation from cardiac arrest.. Prospective, nonrandomized, controlled study using a swine model of cardiac arrest and resuscitation.. After anesthesia, intravascular pressure instrumentation, and ten minutes of ventricular fibrillation arrest, closed-chest CPR was begun. After three minutes of CPR, animals were allocated to receive either 0.02 mg/kg i.v. standard-dose epinephrine (eight) or 0.2 mg/kg i.v. high-dose epinephrine (nine). The animals underwent thoracotomy and rapid-freezing transmural myocardial core biopsy for high-energy phosphate analysis 3.5 minutes after epinephrine administration. High-energy phosphate values were blindly determined using high-pressure liquid chromatography.. Intravascular pressure (mm Hg) and high-energy phosphate (nmol/mg protein) results for standard-dose epinephrine versus high-dose epinephrine are, respectively, coronary perfusion pressure, 15.3 +/- 7.8 versus 23.7 +/- 5.5 (P = .0009); phosphocreatine, 0.4 +/- 0.8 versus 6.2 +/- 4.4 (P = .0003); adenosine triphosphate, 9.8 +/- 4.8 versus 12.7 +/- 5.7 (P = .30); adenosine diphosphate, 5.4 +/- 2.1 versus 6.1 +/- 1.3 (P = .41); and adenylate charge, 0.68 +/- 0.12 versus 0.72 +/- 0.12 (P = .87).. High-dose epinephrine does not deplete myocardial high-energy phosphate when given in this model of prolonged ventricular fibrillation. High-dose epinephrine increases coronary perfusion pressure compared with standard-dose epinephrine. High-dose epinephrine administration repletes phosphocreatine during closed-chest CPR, thereby increasing myocardial energy stores.

Topics: Adenosine; Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Biopsy; Blood Gas Analysis; Cardiopulmonary Resuscitation; Chromatography, High Pressure Liquid; Clinical Protocols; Disease Models, Animal; Drug Evaluation, Preclinical; Epinephrine; Guanosine Triphosphate; Heart Arrest; Hemodynamics; Injections, Intravenous; Inosine; Inosine Monophosphate; Myocardium; Phosphocreatine; Swine; Ventricular Fibrillation

The relationships between pressure rate product (PRP) and flux (PCr-->ATP) or flux(Pi-->ATP) were studied in isolated perfused rat hearts by the method of saturation transfer using 31P-NMR during the preischemic and reperfusion periods. The hearts were made ischemic for 15 min, followed by 60 min of reperfusion. PRP was almost completely depressed, and recovered to 60% of the control level (preischemic period) after reperfusion. The ATP level during reperfusion was significantly decreased, whereas there was no significant change in PCr level. Pi level of reperfused hearts was significantly higher than that in the control. Both flux(PCr-->ATP) and flux(Pi-->ATP) were significantly decreased during the reperfusion period (both p < 0.05). However, the flux(PCr-->ATP)/PRP ratio during reperfusion did not differ from that of the control. This result indicates that the decrease in flux(PCr-->ATP) was matched by a similar decrease in cardiac performance. In contrast, the flux(Pi-->ATP)/PRP ratio during reperfusion was significantly decreased compared to that of control. These results suggest that the stunned heart needs less ATP turnover in proportion to its depressed contractile activity, and flux(Pi-->ATP) may lmit the recovery of postischemic performance.

Topics: Adenosine Triphosphate; Animals; Disease Models, Animal; Magnetic Resonance Spectroscopy; Male; Myocardial Ischemia; Myocardial Reperfusion; Phosphocreatine; Phosphorus; Rats; Rats, Wistar; Ventricular Function, Left

It was the aim of this study to evaluate the effects of hyperthyroidism on heart function and cardiac energy metabolism of spontaneously hypertensive (SHR) rats. Hyperthyroidism was induced by daily injections of T3 (0.2 mg/kg s.c.) for 14 days. The hearts were then isolated and perfused in the Langendorff mode. ATP, phosphocreatine (PCr), and inorganic phosphate (Pi) were measured continuously by means of 31P-nuclear magnetic resonance (NMR) spectroscopy. Work load was altered by varying stepwise the Ca++ concentration in the perfusion fluid from 0.5 to 1.0, 1.5, and 2.0 mM, respectively. At every elevation of the Ca++ concentration, the increase in left ventricular developed pressure (LVDP) was higher in the hyperthyroid SHR than in the untreated SHR hearts. The ATP and PCr concentrations were lower in the hyperthyroid SHR compared to the untreated SHR hearts throughout the perfusion period. PCr decreased at every Ca++ elevation in both the untreated and hyperthyroid SHR hearts. The PCr/ATP ratio was not altered at any Ca++ concentration neither in the untreated SHR nor in the hyperthyroid SHR hearts. The Ca(++)-induced stepwise elevation in LVDP was higher at any given PCr/Pi ratio in the hyperthyroid SHR than in the untreated SHR hearts. Thus, the Ca(++)-inducible contractile reserve was greater in the hyperthyroid SHR heart.

Topics: Adenosine Triphosphate; Animals; Calcium; Cardiomyopathy, Hypertrophic; Disease Models, Animal; Energy Metabolism; Female; Heart; Hyperthyroidism; Magnetic Resonance Spectroscopy; Myocardial Contraction; Perfusion; Phosphocreatine; Rats; Rats, Inbred SHR

The aim of this study was to correlate function of rat ischemic skeletal muscle directly with energy metabolism, to investigate the effects of torbafylline, a novel xanthine derivative potentially useful for the treatment of peripheral vascular occlusive disease and other ailments of skeletal muscle, and to get insight into its mechanism of action. Phosphocreatine (PCr), inorganic phosphate (Pi) and pH were estimated at rest, during induced contractions and during the recovery phase after cessation of electrical stimulation in rat hind limb muscles with two weeks unilateral chronic ligation of the femoral artery. Concomitantly, contraction force was measured in terms of tension developed during the stimulation interval. The effects of torbafylline [7-ethoxymethyl-1-(5-hydroxy-5-methylhexyl)3-methylxanthine] on the above parameters were studied after chronic oral gavage (25 mg/kg body weight per day); treatment started the day after surgery and the last drug application was performed the day of the final experiments. Control animals received physiological saline under the same conditions. During rest no major differences could be detected either in PCr and Pi levels or in pH between the different muscles, ischemic or not and treated or not. During compelled contractions, PCr and pH decreased and Pi increased in all muscles. Differences between muscles and treatments emerged as the PCr drop was more pronounced in ischemic saline treated muscles and the Pi increase in drug treated muscles (normal and ischemic) were clearly less marked than in saline treated ones. Contraction force decreased rapidly during the 12 min electrical direct stimulation and fatigability increased from 67% in normal muscle to 88% in ischemic muscle. Drug treatment induced strikingly less fatigability as it was 44.5% in normal and only 62% in ischemic muscle. However, most marked differences in metabolite levels and pH were measured during the recovery period. As an indication of disturbed energy balance, the recovery of PCr, Pi and pH was seriously hampered in ischemic saline treated muscles; especially pH being still significantly decreased during the entire chosen recovery period of 15 min. Torbafylline not only restored function, but also helped the muscle recover faster and better from exhaustion, as all the parameters returned gradually to normal levels.

Topics: Animals; Disease Models, Animal; Electric Stimulation; Hydrogen-Ion Concentration; Ischemia; Magnetic Resonance Spectroscopy; Male; Muscle Contraction; Muscles; Pentoxifylline; Phosphates; Phosphocreatine; Rats; Rats, Wistar

The effects of dichloroacetate (DCA) on brain lactate, intracellular pH (pHi), phosphocreatine (PCr), and ATP during 60 min of complete cerebral ischemia and 2 h of reperfusion were investigated in rats by in vivo 1H and 31P magnetic resonance spectroscopy; brain lactate, water content, cations, and amino acids were measured in vitro after reperfusion. DCA, 100 mg/kg, or saline was infused before or immediately after the ischemic period. Preischemic treatment with DCA did not affect brain lactate or pHi during ischemia, but reduced lactate and increased pHi after 30 min of reperfusion (p < 0.05 vs. controls) and facilitated the recovery of PCr and ATP during reperfusion. Postischemic DCA treatment also reduced brain lactate and increased pHi during reperfusion compared with controls (p < 0.05), but had little effect on PCr, ATP, or Pi during reperfusion. After 30 min of reperfusion, serum lactate was 67% lower in the postischemic DCA group than in controls (p < 0.05). The brain lactate level in vitro was 46% lower in the postischemic DCA group than in controls (p < 0.05). DCA did not affect water content or cation concentrations in either group, but it increased brain glutamate by 40% in the preischemic treatment group (p < 0.05). The potential therapeutic effects of DCA on brain injury after complete ischemia may be mediated by reduced excitotoxin release related to decreased lactic acidosis during reperfusion.

Topics: Adenosine Triphosphate; Animals; Brain Ischemia; Cations; Dichloroacetic Acid; Disease Models, Animal; Glutamates; Glutamic Acid; Hydrogen-Ion Concentration; Lactates; Lactic Acid; Magnetic Resonance Spectroscopy; Male; Phosphocreatine; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Water

Experimental thermal brain injury leads to significant reduction of glucose utilization in the damaged hemisphere particularly evident in the cortex 3 days after the injury. The rate of development of these changes is not parallel with the observed damage to the blood-brain barrier, coexistent brain oedema and slight disturbances of cerebral blood flow. In a series of experiments it was possible to demonstrate significant accumulation of glucose, high-energy phosphate compounds and their metabolites in the areas of the brain near the damaged part. The authors think that this is an evidence of reduced glucose uptake by the brain resulting from reduced energy needs of the damaged brain tissue despite sufficient supply of energy-yielding substances. Since cerebral metabolism and functions are in close interrelationship reduced glucose metabolism in the damaged tissue leads to reduced activity of the cortex, which contributes to transient (or permanent) functional neurological deficits observed after cranio-cerebral trauma in humans. The knowledge and understanding of these processes regulating the development of local depression of cerebral metabolic processes may help in better results of treatment in such cases.

Topics: Adenosine Triphosphate; Animals; Brain; Brain Diseases, Metabolic; Brain Edema; Cold Temperature; Disease Models, Animal; Female; Glucose; Glycolysis; Male; Phosphocreatine; Rats; Rats, Inbred Strains; Time Factors

Tirilazad mesylate (U74006F) has been reported to improve recovery following cerebral ischemia. We conducted a randomized blinded study to determine if the drug would improve immediate metabolic recovery after complete cerebral compression ischemia.. Mongrel dogs were anesthetized with pentobarbital and fentanyl and treated with either vehicle (citrate buffer, n = 8) or tirilazad (1.5 mg/kg i.v. plus 0.18 mg/kg/hr, n = 8). Normothermic complete cerebral compression ischemia was produced for 12 minutes by lateral ventricular fluid infusion to raise intracranial pressure above systolic arterial pressure. Cerebral high-energy phosphate concentrations and intracellular pH were measured by phosphorus magnetic resonance spectroscopy. Cerebral blood flow was measured with radiolabeled microspheres, and oxygen consumption was calculated from sagittal sinus blood samples. Somatosensory evoked potentials were measured throughout the experiment.. During ischemia, both groups demonstrated complete loss of high-energy phosphates and a fall in intracellular pH (vehicle, 5.76 +/- 0.23; tirilazad, 5.79 +/- 0.26; mean +/- SEM). At 180 minutes of reperfusion, there were no differences between groups in recovery of intracellular pH (vehicle, 6.89 +/- 0.07; tirilazad, 6.88 +/- 0.18), phosphocreatine concentration (vehicle, 89 +/- 16%; tirilazad, 94 +/- 24% of baseline value), oxygen consumption (vehicle, 2.6 +/- 0.2 ml/min/100 g; tirilazad, 1.8 +/- 0.5 ml/min/100 g), or somatosensory evoked potential amplitude (vehicle, 11 +/- 6%; tirilazad, 7 +/- 4% of baseline value). Forebrain blood flow fell below baseline levels at 180 minutes of reperfusion in the tirilazad-treated animals but not in the vehicle-treated dogs (vehicle, 28 +/- 4 ml/min/100 g; tirilazad, 18 +/- 5 ml/min/100 g).. We conclude that tirilazad pretreatment does not improve immediate metabolic recovery 3 hours following 12 minutes of normothermic complete ischemia produced by cerebral compression.

Topics: Animals; Brain Ischemia; Cerebrovascular Circulation; Disease Models, Animal; Dogs; Evoked Potentials, Somatosensory; Injections, Intraventricular; Magnetic Resonance Spectroscopy; Oxygen Consumption; Phosphates; Phosphocreatine; Pregnatrienes; Regional Blood Flow; Reperfusion Injury

In this study we compared the effect of sepsis on muscle protein metabolism in infant (3 to 4 weeks) and adult (3 to 4 months) rats. Sepsis was induced by cecal ligation and puncture (CLP). Control animals underwent sham operation. Sixteen hours after CLP or sham operation, metabolic studies were performed in incubated intact extensor digitorum longus muscles from infant rats or in strips of the same muscle from adult rats. Protein synthesis rate was determined as incorporation of 3H-phenylalanine into protein; total and myofibrillar protein breakdown rates were determined as release of tyrosine and 3-methylhistidine, respectively. Mortality rate following CLP was similar in both age groups. Basal protein synthesis rate was 3 times higher, total protein breakdown rate was 50% higher, and myofibrillar protein breakdown rate was 3 times higher in infant than in adult animals. However, the relative changes in protein turnover rates induced by sepsis were similar in infant and adult rats: protein synthesis rate decreased by approximately 30%, total protein breakdown increased by 40% to 50%, and myofibrillar protein breakdown increased severalfold. The data suggest that despite prominent differences in basal protein turnover rates between infant and adult rats, the effect of sepsis on muscle protein metabolism is not age dependent.

Topics: Adenosine Triphosphate; Age Factors; Animals; Bacterial Infections; Cecum; Disease Models, Animal; Ligation; Male; Methylhistidines; Muscle Proteins; Muscles; Phosphocreatine; Rats; Rats, Sprague-Dawley; Tyrosine

To determine whether cardiac hypertrophy secondary to chronic renovascular hypertension is associated with altered in vivo myocardial metabolism, phosphorus-31 nuclear magnetic resonance saturation transfer techniques were used to study creatine kinase (CK) kinetics in six chronically hypertensive dogs with moderate cardiac hypertrophy and eight control dogs. The forward rate constant of CK and the flux of phosphocreatine to adenosine triphosphate were determined in both groups of dogs before and during norepinephrine administration (1 microgram/kg per min), used to increase heart rate x systolic blood pressure (rate-pressure product), cardiac output and oxygen consumption. Baseline and norepinephrine-induced changes in rate-pressure product, cardiac output and oxygen consumption were similar in both groups of dogs, as were baseline forward rate constant and flux of phosphocreatine to adenosine triphosphate. However, the norepinephrine-induced changes in forward rate constant and flux were significantly less in hypertensive than in control dogs (p less than 0.05) even though changes in hemodynamic and functional variables were similar in both groups. These data demonstrate that moderate myocardial hypertrophy is associated with altered CK kinetics, which do not appear to affect the heart's ability for global mechanical recruitment at this stage in the hypertensive process. It is possible that the changes in myocardial enzyme kinetics may contribute to diastolic dysfunction previously reported in this model and may be a precursor for ultimate development of heart failure if hypertension is maintained for prolonged periods.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adenosine Triphosphate; Animals; Cardiomegaly; Chronic Disease; Creatine Kinase; Disease Models, Animal; Dogs; Echocardiography; Epinephrine; Heart; Hypertension, Renovascular; Kinetics; Magnetic Resonance Spectroscopy; Myocardium; Phosphocreatine; Phosphorus Radioisotopes

An experimental model of optic nerve ischemia was designed in the rabbit to determine early biochemical alterations, i.e.--changes of high energy phosphate metabolites (ATP and phosphocreatine)--in occlusive and peri-occlusive areas. Vascular occlusion provoked a rapid fall of ATP and phosphocreatine in the optic nerve. Free radicals scavengers, superoxide dismutase plus catalase or dimethylthiourea were able to counteract the drop of phosphate metabolites in the peri-occlusive area. These results show that hypoxia leads to oxygen-derived free radical generation which can be responsible for cell damage and emphasize the role of free radicals in the pathogenesis of ocular diseases related to vascular dysfunction.

Topics: Adenosine Triphosphate; Animals; Catalase; Disease Models, Animal; Free Radical Scavengers; Free Radicals; Ischemia; Optic Nerve; Oxygen Consumption; Phosphocreatine; Rabbits; Superoxide Dismutase; Thiourea

Spatially resolved 31P magnetic resonance spectroscopy (MRS) at 4.7 T was applied to noninvasively assess liver phosphorus metabolites in a biochemically well-characterized model of hepatotoxicity induced by injection of a sublethal dose of D-galactosamine (galN). A newly developed hybrid method based on spectral localization with B0 and B1 gradients was employed to obtain multivoxel spectra in intact anesthesized rats. Spatially localized in vivo spectra were recorded 0 to 26 h after galN injection of female rats. In response to galN exposure, diphosphodiester peaks ascribed to UDP-hexosamines became detectable by 4 h and persisted up to 26 h. A metabolite coresonating with inorganic phosphate increased rapidly in intensity by 2 h after galN and returned to baseline by 18 h; this resonance was shown not to be Pi and was assigned to galN-1-phosphate by subsequent high resolution MRS experiments on extracts prepared from these livers. These results confirmed in vivo the metabolic perturbations described previously for this model of hepatotoxicity following biochemical studies based on classical extraction methods. Unlike the in vitro studies, however, these noninvasive experiments provided additional information on the time course of metabolic alterations on the same animal.

Topics: Adenosine Triphosphate; Animals; Chemical and Drug Induced Liver Injury; Disease Models, Animal; Female; Galactosamine; Liver Diseases; Magnetic Resonance Spectroscopy; Phosphocreatine; Phosphoric Diester Hydrolases; Phosphoric Monoester Hydrolases; Phosphorus; Rats; Rats, Inbred Strains

An animal model of muscle denervation was examined by 31P. magnetic resonance spectroscopy. The experiments demonstrated that there is a significant alteration in high and low energy phosphate metabolites in rabbit muscle after nerve section. The data show that there is an early change in the metabolites which appears to plateau at about six weeks. High resolution spectra of muscle cell extracts demonstrate qualitative alterations in the phosphate resonances found in the phosphodiester and phosphomonoester regions of the spectra. There would seem to be a time-related alteration in these components.

Topics: Adenosine Triphosphate; Animals; Disease Models, Animal; Energy Metabolism; Hindlimb; Hydrogen-Ion Concentration; Magnetic Resonance Spectroscopy; Muscle Denervation; Muscles; Phosphates; Phosphocreatine; Phosphoric Diester Hydrolases; Phosphoric Monoester Hydrolases; Phosphorus; Rabbits

This study compares the metabolic and functional effects of three different models of ischemia in the immature heart. The intent was (1) to develop a model of energy-depleted and functionally depressed heart to be used in subsequent studies of myocardial protection and (2) to characterize the biochemical changes following different interventions. Forty-five minutes of normothermic global ischemia produced severe depletion of adenosine triphosphate and creatine phosphate (greater than 70%) but was associated with 85% +/- 10% recovery of left ventricular function. Postischemic functional depression (less than 30% recovery) could be produced by either (1) extending the ischemic duration to 60 minutes or (2) preceding 45 minutes of ischemia by 60 minutes of hypoxic stress (oxygen tension 25 to 30 mm Hg). Neither of these more severe interventions caused more profound depletion of adenosine triphosphate or creatine phosphate, but hypoxic stress produced marked tissue depletion of glutamate (52%) and aspartate (48%) before aortic clamping. Longer ischemia or preceding hypoxia led to greater myocardial accumulation of lactate (greater than 250 versus 104 mumol/gm dry weight) and succinate (18 versus 11 mumol/gm dry weight) during aortic clamping, p less than 0.05 versus 45 minutes of ischemia) and greater postischemic depression and amino acid (greater than 65% aspartate depletion) and carbohydrate (greater than 50% glycogen depletion) metabolism, p less than 0.05 versus simple ischemia. These findings suggest that more severe ischemic/hypoxic models are needed in immature hearts to produce functional depression, and the biochemical analyses suggest the characteristics of metabolic defects that must be corrected to resuscitate these hearts during surgical correction of congenital defects.

Topics: Adenosine Triphosphate; Amino Acids, Dicarboxylic; Animals; Carboxylic Acids; Coronary Circulation; Disease Models, Animal; Dogs; Glycogen; Lactates; Lactic Acid; Myocardial Reperfusion Injury; Myocardium; Phosphocreatine; Time Factors; Ventricular Function, Left

Sepsis has been reported to cause mitochondrial dysfunction and inhibition of key enzymes that regulate the tricarboxylic acid (TCA) cycle. We investigated the effect of sepsis on high-energy phosphates, glycolytic and TCA cycle intermediates, and specific amino acids that are involved in regulating the size of the TCA cycle pool during changes in metabolic state of the heart. Sepsis was induced in 12 female rats by the cecal ligation and perforation technique under halothane anesthesia; seven control rats underwent cecal manipulation without ligation. At 36-42 h postsurgery, the rats were reanesthetized, the chest was opened, and the hearts were freeze-clamped. Perchloric acid extracts of the hearts were analyzed with fluorometric enzymatic methods and 31P nuclear magnetic resonance spectroscopy. There were no significant differences in the levels of the TCA cycle intermediates or high-energy phosphates between the septic and control rats. The major metabolic changes were the 28% decrease in alanine and the 31% decrease in glutamate in the septic hearts compared with control (P less than 0.05 and P less than 0.005, respectively). Phosphocholine, a component of membrane phospholipids, was increased by 91% in the septic hearts (P less than 0.01). We conclude that sepsis does not impair the TCA cycle or induce significant cellular ischemia in the heart. The increase in phosphocholine may represent significant cellular membrane disruption during sepsis.

Topics: Adenosine Triphosphate; Animals; Blood Pressure; Citric Acid Cycle; Disease Models, Animal; Female; Heart; Heart Rate; Hematocrit; Magnetic Resonance Spectroscopy; Myocardium; NAD; NADP; Phosphocreatine; Phosphorus; Rats; Rats, Inbred Strains; Reference Values; Sepsis

Experimental bladder outlet obstruction in cats was produced by surgical placement of a silastic cuff around the urethra. Two sizes of cuff were used to produce either moderate or severe obstruction. The following is a summary of the short-term effects on bladder function. Obstruction induced a significant increase in the in vivo voiding pressure, in proportion to severity of the obstruction. There were no significant differences between control and obstructed cats in bladder mass, response of the isolated whole bladder to field stimulation or bethanechol, response of isolated bladder strips to field stimulation, bethanechol and ATP, or muscarinic receptor density in the bladder body. Although there were no differences in bladder mass between control and obstructed bladders, the hydroxyproline concentration of the severely obstructed bladders was significantly reduced. Creatine phosphate concentration was also significantly reduced in obstructed bladders. Although all whole cat bladder preparations displayed spontaneous contractile activity during in vitro cystometry, the obstructed bladders had a greater amplitude and frequency of spontaneous contractions with a lower volume threshold. In addition, the obstructed bladders had a greater tetrodotoxin-resistant contractile response to field stimulation. These results suggest that the obstructed cat bladder can compensate for increased outlet resistance without induction of bladder hypertrophy or significant functional changes, as seen in both rat and rabbit.

Topics: Adenosine Triphosphate; Animals; Bethanechol; Bethanechol Compounds; Cats; Disease Models, Animal; Female; Hydroxyproline; In Vitro Techniques; Phosphocreatine; Rabbits; Receptors, Muscarinic; Time Factors; Urinary Bladder; Urinary Bladder Neck Obstruction

The electrophysiologic effects of phosphocreatine were assessed in isolated, superfused guinea pig ventricular tissues to gain an insight into its purported antiarrhythmic properties. Under normal conditions, 10 mM phosphocreatine significantly increased effective refractory period by 14.0 +/- 0.4%, but under ischemic-like conditions (hypoxia, hyperkalemia, acidosis) it showed no significant effect. Moreover, phosphocreatine reduced free [Ca2+]0 by nearly 20% and the changes induced by this compound in control tissues could be largely reproduced with an altered Tyrode's solution containing less than 0.6 mM Ca2+. The experiments suggest that phosphocreatine may act in a similar manner as class III antiarrhythmic agents on non-ischemic, normal tissue by mechanisms related in part to changes in extracellular Ca2+ composition.

Topics: Action Potentials; Animals; Anti-Arrhythmia Agents; Coronary Disease; Disease Models, Animal; Guinea Pigs; Heart Ventricles; In Vitro Techniques; Models, Cardiovascular; Myocardium; Phosphocreatine; Purkinje Fibers; Ventricular Function

Treatment of CNS trauma with the opiate antagonist naloxone improves outcome, though the mechanisms of action remain speculative. Nalmefene is another opiate-receptor antagonist, but it has substantially greater potency and duration of action than naloxone. It also has increased activity at kappa opiate receptors and has recently been shown to limit histological changes and neurological dysfunction after traumatic spinal cord injury. The present study examined the effects of treatment with nalmefene on outcome after fluid-percussion-induced traumatic brain injury in rats, using magnetic resonance spectroscopy to monitor acute metabolic changes and behavioral tests to determine chronic neurological recovery. Single-dose treatment with nalmefene (100 micrograms/kg, i.v.) at 30 min after trauma significantly improved (p less than 0.05) neurological outcome (up to 4 weeks) as compared to saline-treated controls. Early changes in intracellular free-magnesium concentration, adenosine diphosphate concentration, and cytosolic phosphorylation potential were all significantly improved by nalmefene treatment, reflecting improved bioenergetic state. We suggest that the ability of nalmefene to improve cellular bioenergetics after trauma may in part account for the neuroprotective effects of this and related compounds.

Topics: Adenosine Triphosphate; Animals; Blood Pressure; Brain Injuries; Disease Models, Animal; Energy Metabolism; Magnesium; Magnetic Resonance Spectroscopy; Male; Motor Activity; Naltrexone; Narcotic Antagonists; Phosphates; Phosphocreatine; Phosphorus; Rats; Rats, Inbred Strains

We studied the brain metabolism in macular mutant mice (Ml/y, +/y), an appropriate model of Menkes kinky hair disease, using 31P- and 1H-NMR spectroscopy to clarify the pathophysiological mechanisms of disturbed nervous function. An analysis of in vivo 31P-NMR spectra showed a decreased phosphocreatine (PCr)/inorganic phosphate (Pi) ratio and decreased ATP levels and decreased intracellular pH in Ml/y mice at 9 days, suggesting energy failure in the brain. This associated decline in ATP levels may reflect multiple causative factors including disturbed mitochondrial respiration and ischemia secondary to circulatory failure. Brain metabolites, including PCr, creatine, lactate and 7 amino acids were easily detectable quantitatively and qualitatively by in vitro 1H-NMR spectrum. An elevation in lactate levels and a decline in PCr/creatine ratio in Ml/y mice at 9 days were also noted with an in vitro study, supporting the in vivo data. NMR spectroscopy is a useful and promising tool to obtain the information on brain metabolism.

Topics: Amino Acids; Animals; Brain; Disease Models, Animal; Energy Metabolism; Lactates; Lactic Acid; Magnetic Resonance Spectroscopy; Menkes Kinky Hair Syndrome; Mice; Mice, Inbred C3H; Phosphocreatine

Serial proton (1H) and phosphorus-31 (31P) magnetic resonance (MR) spectroscopy of cerebral infarction was performed in rats to assess the sensitivity of these techniques for use in clinical cerebral infarction. In this experimental chronic infarction model, 31P spectroscopy tended to return to a "normal" pattern within 24 hours after induction of infarction in spite of pathologically proven completed infarction and, therefore, appeared not to be sensitive enough for clinical application. On the other hand, proton spectroscopy invariably showed persistent high lactate levels and was capable of distinguishing completed infarction from reperfused recovered brain. Persistent high lactate levels appear to be a good MR spectroscopic indicator of completed infarction.

Topics: Animals; Cerebral Infarction; Disease Models, Animal; Lactates; Magnetic Resonance Spectroscopy; Phosphates; Phosphocreatine; Rats; Rats, Inbred Strains

We have developed an animal model to elucidate the acute effects of perfusion abnormalities on muscle metabolism induced by different density-defined classes of erythrocytes isolated from sickle cell anemia patients. Technetium-99m (99mTc)-labeled, saline-washed normal (AA), homozygous sickle (SS), or high-density SS (SS4) erythrocytes were injected into the femoral artery of the rat and quantitative 99mTc imaging, 31P magnetic resonance spectroscopy by surface coil at 2 teslas, and 1H magnetic resonance imaging at 0.15 tesla were performed. Between 5 and 25 microliters of SS4 cells was trapped in the microcirculation of the thigh (or 1-6 x 10(7) cells per cubic centimeter of tissue). In contrast, fewer SS discocytes (SS2) or AA cells were trapped (an equivalent packed cell volume of less than 6.7 microliters and 0.3 microliters, respectively). After injection of SS4 cells an initial increase in inorganic phosphate was observed in the region of the thigh served by the femoral artery, intracellular pH decreased, and subsequently the proton relaxation time T1 reached a broad maximum at 18-28 hr. When T1 obtained at this time was plotted against the volume of cells trapped, an increase of T1 over the control value of 411 +/- 48 msec was found that was proportional to the number of cells trapped. We conclude that the densest SS cells are most effective at producing vasoocclusion. The extent of the change detected by 1H magnetic resonance imaging is dependent on the amount of cells trapped in the microcirculation and the magnitude of the initial increase of inorganic phosphate.

Topics: Anemia, Sickle Cell; Animals; Disease Models, Animal; Energy Metabolism; Erythrocytes, Abnormal; Humans; Hydrogen-Ion Concentration; Leg; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Microcirculation; Phosphocreatine; Rats; Vascular Diseases

In the experiments on rats the peptic ulcer of duodenum was simulated by means of mechanic compression of reflexogenic zones of pylorus and intestine. The destruction of duodenal mucosa was developed in 3-4 hours after the compression and retained in the course of 5-6 days. Piracetam (200 mg/kg) and etimizol (3 mg/kg) eliminated and cimetidine (25 mg/kg), solcoseryl (0.5 mg/kg) and metacine (5 mg/kg) diminished the destruction after the course of 6 injections of each drug with an interval of 10-12 hours. Therapeutic effects of piracetam and etimizol correlated with their ability to return towards normal concentration of creatine phosphate.

Topics: Animals; Disease Models, Animal; Drug Evaluation, Preclinical; Duodenal Ulcer; Duodenum; Energy Metabolism; Male; Phosphocreatine; Psychotropic Drugs; Rats; Time Factors

The first nuclear magnetic resonance spectroscopic study of the canine pancreas is described. Both in-vivo, ex-vivo protocols and nmr observables are discussed. The stability of the ex-vivo preparation based on the nmr observables is established for at least four hours. The spectra obtained from the in-vivo and ex-vivo preparations exhibited similar metabolite ratios, further validating the model. Metabolite levels were unchanged by a 50% increase in perfusion rate. Only trace amounts of phosphocreatine were observed either in the intact gland or in extracts. Acute alcoholic pancreatitis was mimicked by free fatty acid infusion. Injury resulted in hyperamylasemia, edema (weight gain), increased hematocrit and perfusion pressure, and depressed levels of high energy phosphates.

Topics: Alcoholism; Animals; Disease Models, Animal; Dogs; Magnetic Resonance Spectroscopy; Oleic Acid; Oleic Acids; Pancreas; Pancreatitis; Phosphocreatine; Phosphorus Radioisotopes

Phosphorus-31 magnetic resonance spectroscopy was used to study the relationship between metabolic and functional alterations during acute regional ischemia in vivo. Phosphocreatine, adenosine triphosphate (ATP), inorganic phosphate, and intracellular pH (pHi) were monitored in 11 pigs at 2-minute intervals during 4 and 20 minutes of acute left anterior descending coronary artery occlusion followed by 20 minutes of reperfusion. In a parallel series of experiments, segment shortening was continuously monitored by sonomicrometry during the early ischemic period. Segment shortening decreased precipitously after coronary occlusion, and systolic expansion was noted within 30 seconds. Phosphocreatine levels decreased rapidly and reached a minimum value of 44 +/- 13% (mean +/- SE) of the control value by 20 minutes of ischemia. Ischemia-induced reduction of ATP was small and not statistically significant. Inorganic phosphate increased rapidly to a peak level of 158 +/- 9% of the control value by 4 minutes of ischemia. Intracellular pH decreased 0.76 +/- 0.04 units during the initial 10 minutes of ischemia and subsequently stabilized. After reperfusion, phosphocreatine, inorganic phosphate, and pHi recovery occurred within 4 minutes and was similar in the 4- and 20- minute ischemia groups. These results indicate that the changes in high-energy phosphates and pHi observed during both 4 and 20 minutes of coronary occlusion are rapidly reversible. The temporal course of metabolic and functional alterations during early ischemia suggests that if these are causally related the decline in contractility is mediated by an increase in inorganic phosphate, a decrease in pHi, or both rather than by loss of ATP.

Topics: Adenosine Triphosphate; Animals; Biopsy; Constriction; Coronary Disease; Coronary Vessels; Disease Models, Animal; Hemodynamics; Hydrogen-Ion Concentration; Intracellular Fluid; Magnetic Resonance Spectroscopy; Myocardial Contraction; Myocardium; Perfusion; Phosphates; Phosphocreatine; Phosphorus Isotopes; Swine

Isolated hearts from normal and cardiomyopathic hamsters (160 to 180 days of age) were perfused through the aorta and assessed by echocardiographic and 31P-NMR (nuclear magnetic resonance) techniques. A decreased left ventricular systolic pressure in cardiomyopathic hamsters was associated with diminished cardiac size and left ventricular wall thickness. However, the ratio of inner/outer cross-sectional area and estimated left ventricular volume at any given left ventricular weight was significantly higher, indicating relative left ventricular chamber enlargement in cardiomyopathic hamsters. Left ventricular volumes were increased with an intraventricular balloon. Gradual inflation of the balloon resulted in increments of left ventricular systolic and developed stress that rose to the same values in both groups. At this point, the normalized stress-strain relationship was approximately two times steeper for cardiomyopathic hamsters, while at lower strain values the diastolic stress in cardiomyopathic hamsters was less than in controls, possibly due to cardiac dilatation. Almost the same degree of dilatation was induced in control hearts by the acute addition of 1% alcohol, but it was not followed by increased diastolic stiffness. Examination of hearts by 31P-NMR techniques revealed a decreased phosphocreatine/inorganic phosphate (PCr/Pi) ratio in the cardiomyopathic hamsters that progressed further with balloon inflation and was associated with a relative fall in PCr and adenosine triphosphate (ATP) content. Results suggest increased diastolic stiffness in cardiomyopathic hamsters, which was not seen in acute cardiac depression with alcohol. Diastolic volume overload with increased wall stress is probably the major factor contributing to increased diastolic stiffness early in the cardiomyopathy.

Topics: Adenosine Triphosphate; Animals; Blood Pressure; Cardiomyopathies; Cricetinae; Disease Models, Animal; Echocardiography; Ethanol; Heart; Heart Ventricles; Mesocricetus; Myocardium; Phosphates; Phosphocreatine

Bladder outlet obstruction has been the subject of numerous studies. In previous studies on severe obstruction, the initial response of the bladder has been to produce an acute overdistension of the bladder resulting in severe tissue damage and functional disorders. This is quite different from the slow onset of outlet obstruction seen in association with benign prostatic hypertrophy (BPH). The present study describes the functional effect of mild outlet obstruction created in a rabbit model, and compares it to a previously described model of severe obstruction. Mild bladder outlet obstruction was created by placing a silicon sleeve (inner circumference 30 mm.) around the bladder neck of mature male NZW rabbits. Individual groups of rabbits were studied at one, seven, and 14 days following the creation of the outlet obstruction. The following studies were performed on each group of rabbits: in vivo and in vitro cystometry, field stimulation and cholinergic stimulation using the in vitro whole bladder model. In addition, the tissue concentration of ATP (adenosine triphosphate) and CP (creatine phosphate) and the muscarinic receptor density were determined. The obstructed bladders showed no significant cystometric difference at one day, but revealed a marked decrease of compliance and capacity at one and two weeks. Unlike the response to severe outlet obstruction, there was no initial acute overdistension of the bladder wall. Although the ability of the obstructed bladders to generate intravesical pressure in response to both field stimulation and bethanechol did not decrease, the ability of both forms of stimulation to empty the obstructed bladders was markedly impaired. The response to field stimulation was reduced to a significantly greater extent than the response to bethanechol, indicating neuronal damage. The muscarinic receptor number per bladder was increased above control at all time periods. The intracellular concentration of ATP and CP in the obstructed bladders was similar to that of control. Our present model of mild obstruction was not accompanied by a massive increase in tissue mass nor was there an overdistension of the detrusor; thus, this model would be a more suitable model for the study of clinical outlet obstruction.

Topics: Adenosine Triphosphate; Animals; Disease Models, Animal; Male; Organ Size; Phosphocreatine; Rabbits; Receptors, Muscarinic; Urinary Bladder; Urinary Bladder Neck Obstruction; Urodynamics

Myocardial exogenous substrate preference was studied under conditions of increased plasma lactate concentration before and after a severe (halving of tissue ATP concentration, sixfold increase in tissue lactate concentration) but reversible (less than 1% necrosis on reperfusion) global ischaemic stress produced by continuous hypothermic electromechanical arrest of the heart of four hours' duration by aortic cross clamping and multidose potassium cardioplegia. Fatty acid oxidation was studied using 1-14C-palmitate under steady state conditions and under similar isovolumic fixed pressure conditions with the heart at a constant rate using a left ventricular intracavitary balloon. Exogenous free fatty acid oxidation during the pre-ischaemic period with an increased lactate concentration (3.9-5.8 mmol . litre-1) was 0.62(0.21) mumol . min-1 X 100 g-1 (mean (SEM)). This represented a mean of 32% of the total carbon dioxide produced in contrast to a post-ischaemia free fatty oxidation rate of 2.67(0.87) mumol . min-1 X 100 g-1, in the presence of even further increased plasma lactate concentrations (8.47-11.17 mmol . litre-1), representing a mean of 82% of the total carbon dioxide output. These data suggest that the substrate preference of the myocardium, under conditions of increased plasma lactate concentration, shifts to greater oxidation of exogenous free fatty acids after ischaemic stress.

Topics: Adenosine Triphosphate; Animals; Coronary Disease; Disease Models, Animal; Dogs; Fatty Acids, Nonesterified; Glycogen; Heart; Lactates; Myocardial Contraction; Myocardium; Oxygen; Phosphocreatine

A small animal model of arterial insufficiency is presented which involves unilateral femoral artery ligation and section. Invoked alterations in metabolism and perfusion of the affected muscle mass have been investigated 12 h, 4, 7 and 14 days post-ligation by 31P-n.m.r. and microsphere infusion, both at rest and during isometric muscle contraction at 1 Hz. At rest, the concentration of phosphocreatine was similar to the mean control value (36.0 +/- 1.0 mM) from 4 days post-ligation, but was significantly lower at 12 h (28.5 +/- 3.6 mM). Inorganic phosphate concentrations were significantly elevated for 7 days post-ligation. No significant differences were noted in intramuscular pH. Upon stimulation of the affected muscle mass, a time-dependent improvement in phosphocreatine utilization was observed such that 14 days post-ligation phosphocreatine utilization was not significantly different from mean control values. A similar amelioration was noted for the contraction-induced fall in intramuscular pH. At rest, no significant differences in bloodflow to the muscles of the ligated limb compared with the unaffected contralateral limb were observed. However, isometric contraction of the affected muscle mass resulted in a markedly reduced hyperaemic response 12 h post-ligation. Thereafter, a time-dependent improvement in tissue perfusion during stimulation was observed which paralleled the improvements in phosphocreatine utilization and intramuscular pH changes. The results presented are discussed with respect to the interrelationship between oxygen delivery, high energy phosphate utilization and force maintenance.

Topics: Animals; Disease Models, Animal; Electric Stimulation; Hindlimb; Ischemia; Magnetic Resonance Spectroscopy; Male; Muscle Contraction; Muscles; Phosphates; Phosphocreatine; Rats; Rats, Inbred Strains; Regional Blood Flow

A congestive cardiomyopathy (CCM) model occurs in inbred broad-breasted turkeys and is manifested by reduced hatchability and a high mortality within a week of hatching. In the survivors, cardiac dilation begins by 3-4 weeks of age and further mortality occurs from chronic congestive heart failure. The mechanisms behind these changes is unknown, and, therefore, we investigated what role, if any, myocardial energy metabolism might play in these events. Ventricular myocardial samples were obtained for analysis of adenine nucleotides (ATP, ADP, AMP) and creatine phosphate (CP) in control and CCM turkeys, 1-31 days old. The adenine nucleotide energy charge (EC) was calculated using the formula EC = ATP + 1/2ADP/(ATP + ADP + AMP). We found the myocardial ATP levels and EC in CCM hearts at 1-2 days were reduced. In control turkeys, no significant age-related differences were found in myocardial high-energy phosphate compounds or in the EC. This depression in the energy metabolism of CCM turkeys may also be reflected in their poor hatchability. By 6-10 days, however, ATP levels had recovered and remained normal despite the onset of cardiac dilation and failure at 3-4 weeks of age in CCM turkeys. Because CP levels in control and CCM turkey hearts were similar in all age groups, significant ischemia did not appear to be present after hatching in CCM turkeys. Our results suggest, therefore, that an insult probably prior to hatching produced depressed myocardial energy levels in CCM turkeys and led to reduced hatchability. This early insult appears to be significant, in that late cardiac dysfunction resulted despite the recovery of myocardial ATP levels.

Topics: Adenine Nucleotides; Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Cardiomyopathy, Dilated; Disease Models, Animal; Myocardium; Phosphocreatine; Turkeys

Quantification by NMR of hypoxic stress is best afforded by the ratio of phosphocreatine (PCr) to inorganic phosphate (Pi). The thin cranium and sternum of neonates affords ideal conditions for NMR evaluation of impaired oxidative metabolism. Brains of animal models (dog and cat) are best studied with muscles retracted with the rf coil placed on the bare skull. 31P and 1H (lactate) signals are time shared with a doubly tuned coil. Servo-stabilized hypoxia gives simplified steady state analysis. Hypoxic insults of the brain are evaluated by the integral of the deviation of the PCr/Pi ratio from the normoxic values. Generally, a deviation of 1 unit of PCr/Pi for an interval of 3 hr will lead to a severe metabolic damage and recovery from hypoxia is often 30-fold delayed. Comprehensive monitoring of energy metabolism (PCr/Pi), respiratory chain redox states, intracellular pH and lactate accumulation allow the calculation of integrated pH and lactate "insults" and thus offer new insights on the effects of hypoxia on brain oxidative metabolism.

Topics: Animals; Brain; Disease Models, Animal; Dogs; Hypoxia; Magnetic Resonance Spectroscopy; Phosphates; Phosphocreatine

Previous studies have suggested that one of the mechanisms of adriamycin (ADR) cardiomyopathy is depletion of high-energy phosphate stores (HEP). To examine this hypothesis, we used 31P nuclear magnetic resonance to assess the adenosine triphosphate-to-phosphocreatine ratio (ATP-to-PCr ratio) in Langendorff-perfused rabbit hearts. Using either an acute (5 days of therapy at 5 mg/kg/day) or chronic model (7 to 10 weeks of therapy at 1.2 or 1.5 mg/kg twice a week), we compared isovolumetric LV systolic pressure, heart rate, ATP-to-PCr ratios, and histologic lesions between the treated and control animals in each model. In the acute model, there was a significant increase in the ATP-to-PCr ratio (P less than 0.02), without significant changes in myocardial function. Despite significant hemodynamic and histologic alterations in the chronic model, compared to controls, we were unable to identify significant differences in ATP-to-PCr ratios. We conclude that there appear to be differences in energy metabolism between the acute cardiotoxicity and the chronic cardiomyopathy of ADR in the rabbit model and the mechanism of the chronic cardiomyopathy from ADR therapy does not appear to be related to progressive impairment of cellular high-energy phosphate metabolism as measured by the ATP-to-PCr ratio.

Topics: Adenosine Triphosphate; Animals; Blood Pressure; Cardiomyopathies; Disease Models, Animal; Doxorubicin; Energy Metabolism; Heart Diseases; Heart Rate; Magnetic Resonance Spectroscopy; Male; Phosphates; Phosphocreatine; Rabbits

Infusion of dinitrophenol intra-arterially into rat hind limb caused an irreversible failure of isometric twitch tension and the induction of a severe progressive contracture. Metabolite analysis of muscle in which the twitch response had grossly fatigued revealed low levels of ATP and phosphocreatine together with lactate accumulation. Studies using 31P-n.m.r. confirmed the decrease in ATP and creatine phosphate concentrations and indicated a fall in intracellular pH. It is concluded that dinitrophenol-induced myopathy does not represent a good model for the human mitochondrial myopathic condition as has been previously suggested.

Topics: 2,4-Dinitrophenol; Adenosine Triphosphate; Animals; Dinitrophenols; Disease Models, Animal; Electric Stimulation; Isometric Contraction; Magnetic Resonance Spectroscopy; Mitochondria, Muscle; Muscular Diseases; Phosphocreatine; Rats; Rats, Inbred Strains; Uncoupling Agents

Earlier we have shown in the dog model mimicking angina on effort a delayed antiischaemic effect of PgI2 and its stable analogue 7-oxo-PgI2-Na, appearing only when the drug induced marked vasodilatation was over [1]. In the present experiments we could show that the protective effect appears at a time when the blood pressure returned to normal and in addition the marked platelet aggregation inhibitory effect has also faded away. In the rat 7-oxo-PgI2 could substantially diminish vasopressine induced T-wave elevation in the ECG if given 2 hours before administration of vasopressin. In addition it could moderate the vasopressin induced metabolic changes appearing as diminution of the myocardial CP and ATP-level and increase of the myocardial lactate content. A similar metabolic protection was found in the heart of rats pretreated with 7-oxo-PgI2 2 hours before taking myocardial samples and exposing them for 1 minute to ischaemia by incubation in Ringer solution. It is concluded that a direct metabolic and hemodynamic effect could be at least partly responsible for the late antiischaemic effect of 7-oxo-PgI2. This effect was also present in the early phase of experimental myocardial infarction in conscious rats if animals were pretreated with 7-oxo-PgI2 2 hours before occlusion. However treatment did not increase survival rate and failed to reduce the incidence and severity of arrhythmias.

Topics: Adenine Nucleotides; Angina Pectoris; Animals; Disease Models, Animal; Dogs; Epoprostenol; Female; Heart; Lactates; Male; Myocardial Infarction; Myocardium; Phosphocreatine; Rats; Rats, Inbred Strains; Vasopressins

The effects of severe global ischemia on cardiac high energy phosphate (HEP) stores were investigated in an in vitro rat model. The heart was removed from the rat in this model, sealed in a plastic bag and incubated for varying times and temperatures (20-45 degrees C). The rat, in the in vivo anoxic model, was subjected to cervical dislocation which resulted in respiratory arrest. In both models the hearts were removed and analyzed for HEP at appropriate times following the onset of anoxia or ischemia. Verapamil and nifedipine, administered intravenously 10 minutes before the start of the experiments, preserved HEP stores in both models. The degree of protection provided by the Ca+2 blockers was related to both the dose of drug and the duration of the ischemia/anoxia. Verapamil was more active than nifedipine in both models.

Topics: Adenine Nucleotides; Animals; Calcium Channel Blockers; Chromatography, High Pressure Liquid; Coronary Disease; Disease Models, Animal; Hypoxia; In Vitro Techniques; Male; Nifedipine; Phosphocreatine; Rats; Rats, Inbred Strains; Temperature; Verapamil

Topics: Adenosine Triphosphate; Animals; Disease Models, Animal; Fructosediphosphates; Glycogen; Glycolysis; Hexosediphosphates; Lactates; Lactic Acid; Male; Muscle Contraction; Muscle Cramp; Muscles; Myoglobinuria; Phosphocreatine; Physical Exertion; Rats; Rats, Inbred Strains

The basis for skeletal muscle dysfunction in phosphate-deficient patients and animals is not known, but it is hypothesized that intracellular phosphate deficiency leads to a defect in ATP synthesis. To test this hypothesis, changes in muscle function and nucleotide metabolism were studied in an animal model of hypophosphatemia. Mice were made hypophosphatemic through restriction of dietary phosphate intake. Gastrocnemius function was assessed in situ by recording isometric tension developed after stimulation of the nerve innervating this muscle. Changes in purine nucleotide, nucleoside, and base content of the muscle were quantitated at several time points during stimulation and recovery. Serum concentration and skeletal muscle content of phosphorous are reduced by 55 and 45%, respectively, in the dietary restricted animals. The gastrocnemius muscle of the phosphate-deficient mice fatigues more rapidly compared with control mice. ATP and creatine phosphate content fall to a comparable extent during fatigue in the muscle from both groups of animals; AMP, inosine, and hypoxanthine (indices of ATP catabolism) appear in higher concentration in the muscle of phosphate-deficient animals. Since total ATP use in contracting muscle is closely linked to total developed tension, we conclude that the comparable drop in ATP content in association with a more rapid loss of tension is best explained by a slower rate of ATP synthesis in the muscle of phosphate-deficient animals. During the period of recovery after muscle stimulation, ATP use for contraction is minimal, since the muscle is at rest. In the recovery period, ATP content returns to resting levels more slowly in the phosphate-deficient than in the control animals. In association with the slower rate of ATP repletion, the precursors inosine monophosphate and AMP remain elevated for a longer period of time in the muscle of phosphate-deficient animals. The slower rate of ATP repletion correlates with delayed return of normal muscle contractility in the phosphate-deficient mice. These studies suggest that the slower rate of repletion of the ATP pool may be the consequence of a slower rate of ATP synthesis and this is in part responsible for the delayed recovery of normal muscle contractility.

Topics: Adenosine Triphosphate; Animals; Base Composition; Disease Models, Animal; Inosine Monophosphate; Mice; Mice, Inbred C57BL; Muscle Contraction; Muscles; Phosphates; Phosphocreatine; Phosphorus

The calcium channel blocker, diltiazem, has been studied in the same model used for evaluation of cold blood-potassium cardioplegia. Six dogs (Group 1) had one hour of myocardial ischemia with topical ice (myocardial temperature, 7 degrees +/- 2 degrees C) after coronary perfusion with 200 ml of cold blood (5 degrees +/- 1 degree C) containing diltiazem, 400 micrograms per kilogram of body weight. Seven dogs (Group 2) had two hours of ischemia after perfusion with 200 ml of cold blood containing 200 micrograms/kg and reperfusion every 30 minutes with 100 ml of cold blood and diltiazem, 100 micrograms/kg. Baseline studies were repeated after rewarming and 40 minutes of reperfusion. No inotropic agents or calcium were used. Heart rate, peak systolic pressure, velocity of the contractile element, peak + rate of rise of left ventricular pressure (dP/dt), peak - dP/dt, dP/dt over common peak isovolumic pressure, left ventricular compliance and stiffness, and heart water were unchanged in Group 1. In Group 2, heart rate slowed (p less than 0.025) and compliance decreased (p less than 0.02). In both groups, coronary vascular resistance declined (p less than 0.001) and recovery of adenosine triphosphate (p less than 0.001), adenosine diphosphate (p less than 0.025), and the adenosine pool (p less than 0.001) was impaired. Ultrastructure was well preserved, but myofibrillar lesions were noted in Group 2. Diltiazem cardioplegia was associated with good functional recovery, but there was impairment of high-energy phosphate metabolism.

Topics: Adenosine; Animals; Benzazepines; Biopsy; Blood Transfusion; Diltiazem; Disease Models, Animal; Dogs; Heart Arrest, Induced; Hemodynamics; Myocardium; Phosphates; Phosphocreatine

A study was undertaken to evaluate the effect of acute occlusion of a coronary artery during cardioplegic arrest on myocardial preservation and to elucidate the influence of reestablishment of flow versus continued occlusion during the phase of myocardial reperfusion. Coronary occlusion was simulated, and myocardial viability was determined by measuring tissue levels of adenosine triphosphate (ATP) and creatine phosphate (CP) in biopsies of the posterior left ventricular wall. Eighteen pigs were divided into three equal groups consisting of animals with (1) patent right coronary arteries during arrest and reperfusion, (2) occluded right coronary arteries during arrest and patent during reperfusion, and (3) occluded right coronary arteries during arrest and reperfusion. The results of ATP and CP measurements showed that while poorer protection was afforded during two-hour arrest when the coronary artery was occluded, the risk of damage was much greater during reperfusion. Failure to restore adequate blood flow by retention of occlusion caused a concurrent decrease in ATP and CP levels below prescribed limits of myocardial tolerance. When occlusion occurs in the clinical setting, impeding cardioplegia and reperfusion, the importance of revascularization is emphasized.

Topics: Adenosine Triphosphate; Animals; Coronary Disease; Coronary Vessels; Disease Models, Animal; Heart; Heart Arrest, Induced; Hypothermia, Induced; Ligation; Myocardium; Perfusion; Phosphocreatine; Swine

Topics: Adenosine Triphosphate; Animals; Coronary Disease; Disease Models, Animal; Dogs; Lactates; Microscopy, Electron; Myocardium; Phosphocreatine

Using experimental models of various disease states, the ability of the isolated perfused working rat heart to withstand and recover from a period of severe ischemia was investigated. The results revealed that the coexistence of a diabetic state, obesity, or left ventricular hypertrophy increased the susceptibility of the hearts to ischemic damage and reduced the rate or the extent of postischemic recovery. In contrast, hearts obtained from moderately hypertensive rats exhibited a greater resistance to, and a superior recovery from, ischemia than did hearts obtained from normotensive controls.

Topics: Adenosine Triphosphate; Animals; Cardiac Output; Cardiomegaly; Coronary Circulation; Coronary Disease; Diabetes Mellitus, Experimental; Disease Models, Animal; Electrolytes; Heart Arrest, Induced; Hypertension; Male; Myocardial Contraction; Myocardium; Obesity; Phosphocreatine; Procaine; Rats; Triglycerides

Treatment with glucagon in addition to blood transfusion was compared with blood transfusion alone after one hour of hemorrhagic shock in the rat. In liver tissue Na+ increased and K+ decreased during haemorrhagic shock. After treatment the initial values were restored equally in both groups within ten minutes. Incubation of liver slices in cold Krebs' solution resulted in a pronounced increase in Na+ and decrease in K+, the values being partially restored to initial levels after subsequent incubation at 37 degrees. Thirty minutes after treatment the liver slices obtained from rats given glucagon showed a more normal ion composition after leaching and rewarming than slices from rats not given glucagon. ATP decreased and glucose and lactate increased in liver tissue during hemorrhagic shock. These variables were partially restored 30 minutes after treatment. No difference between the treatment groups was noted. Animals trreated with glucagon were, however, more efficient in reducing the elevated blood lactate level. The results suggest that the use of glucagon in the treatment of hemorrhagic shock might be of benefit for cellular function in the liver.

Topics: Adenosine Triphosphate; Animals; Biological Transport; Blood Transfusion; Cell Membrane; Disease Models, Animal; Glucagon; Glucose; Glucosephosphates; Lactates; Liver; Male; Phosphocreatine; Potassium; Rats; Shock, Hemorrhagic; Sodium

Topics: Animals; Arrhythmias, Cardiac; Cats; Coronary Vessels; Disease Models, Animal; Heart Ventricles; Ligation; Myocardial Infarction; Phosphocreatine; Sympathetic Nervous System; Ventricular Fibrillation

An attempt was made to determine the effect of hypothermic potassium cardioplegia (35 mEq of potassium chloride) on the hypertrophic ventricle. Puppies with induced left ventricular hypertrophy were divided into four groups and studied after one hour on global ischemia. Myocardial adenosine triphosphate (ATP) was best preserved in the hypothermically perfused groups and correlated well with measurements of coronary sinus creatine phosphokinase (CPK). In Groups 1 and 2 (anoxic arrest at 37 degrees C and KC1 perfusion at 37 degrees C), CPK at 30 minutes of reperfusion was 1,031 and 198 IU, respectively, compared to 35 IU in Group 3 (KC1 perfusion at 4 degrees C) and 44 IU in Group 4 (Ringer's lactate at 4 degrees C). Myocardial injury was milder in Groups 3 and 4 regardless of whether potassium chloride was added. It is apparent that hypothermic perfusion of a hypertrophic ventricle was the major factor in myocardial preservation, as determined by myocardial ATP and coronary sinus CPK.

Topics: Adenosine Triphosphate; Animals; Cardiomegaly; Creatine Kinase; Disease Models, Animal; Dogs; Electrocardiography; Glycogen; Heart Arrest, Induced; Hypothermia, Induced; Lactates; Myocardial Contraction; Myocardium; Organ Size; Perfusion; Phosphocreatine; Potassium Chloride

Following acute myocardial infarction the functional load of the surviving heart muscle does increase considerably, leading to an increased release of adrenergic neurotransmitters with a consequent decrease in endogenous catecholamine stores. Within the first 24 h following infarction, a temporary decline in the high-energy phosphate content is observed in the surviving heart muscle; futhermore, a reduction in lactate extraction is noted. In the intact organism an increased shortening of the surviving heart muscle is noted as a consequence of the altered ventricular geometry and the increased release of catecholamines. If these effects are excluded by means of isolation and analysis in vitro, a decrease in contractile function could be demonstrated in the surviving heart muscle in the early phase following infarction; the response to positive inotropic interventions was depressed as well. These changes are reversible; six weeks following infarction a normal contractile behaviour is observed.

Topics: Adenosine Triphosphate; Animals; Catecholamines; Disease Models, Animal; Heart; Hemodynamics; In Vitro Techniques; Lactates; Myocardial Contraction; Myocardial Infarction; Myocardium; Norepinephrine; Phosphocreatine; Time Factors

Topics: Adenosine; Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Blood Pressure; Coronary Disease; Disease Models, Animal; Hypoxanthines; Hypoxia; In Vitro Techniques; Inosine; Male; Microspheres; Myocardial Contraction; Myocardium; Perfusion; Phosphocreatine; Polysaccharides; Rats; Sepharose

Insertion of a flow pump into the Langendorff retrograde perfusion apparatus has permitted the production of stable, graded ischemia in hearts whose hemodynamic and metabolic response may be evaluated. Ventricular pressures were monitored with a modified balloon and catheter-tip manometer system, and oxygen consumption , lactate and glucose metabolism, and tissue high-energy phosphate stores measured. A 15-min stabilization period in 56 paced hearts was followed by 15 min of either full, 40, 30, 20, or 10% coronary flow, after which the ventricular tissue was freeze-clamped for tissue assay. Tissue creatine phosphate fell progressively from 23.7 in full flow hearts to 9.9 mumol/g dry wt after 90% reduction in flow. This was accompanied by a graded reduction in ATP from 20.3 to 14.0 mumol/g dry wt and a rise in AMP from 1.1 to 2.6 mumol/g dry wt. Tissue lactate rose progressively from 22.3 to 60.1 mumol/g dry wt. Hemodynamic function correlated with coronary flow. This preparation offers an opportunity to study pharmacological and metabolic interventions in ischemic heart disease.

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Coronary Circulation; Coronary Disease; Disease Models, Animal; Glucose; Glycogen; Hemodynamics; In Vitro Techniques; Lactates; Male; Myocardial Contraction; Myocardium; Oxygen Consumption; Phosphocreatine; Rats

The effects of metabolic accumulation on myocardial metabolism during global heart oxygen deprivation were evaluated in a working in situ swine heart preparation with controlled total coronary blood flow. Myocardial oxygen consumption was depressed to a similar extent by either reducing total coronary flow 60 per cent (ischemia, low coronary perfusion) in 10 swine or by decreasing coronary perfusate PO2 to 30 mm. Hg at normal flows (hypoxemia, high coronary perfusion) in 13 swine. Compared with findings in 13 control hearts, ischemia significantly (p less than 0.05) decreased myocardial oxygen consumption (640 to 390 mumole per hour per gram), glucose uptake (185 to 16 mumole per hour per gram), and free fatty acid consumption (32 to 17 mumole per hour per gram). ttissue levels of glycogen, creatine phosphate, and adenosine triphosphate (tatp) were significantly reduced (p less than 0.005), and tissue lactate, adenosine diphosphate (ADP), and adenosine monophosphate (AMP) were increased (p less than 0.001). During hypoxemia, glucose uptake was increased (240 mumole per hour per gram) and free fatty acid consumption was somewhat less depressed (19 mumole per hour per gram). Creatine phosphate and ATP were higher than with ischemia (p less than 0.01), and lactate, ADP, and AMP accumulations were less (p less than 0.01). Thus, in the period immediately following myocardial oxygen deprivation, inadequate coronary perfusion caused greater metabolic buildup which inhibited myocardial substrate utilization and energy production. High coronary perfusion, even though the perfusate was unoxygenated, was associated with greater preservation of substrate utilization, higher levels of high-energy phosphates, less accumulation of metabolic products, and a longer survival. These data suggest a critical role of coronary perfusion in protecting myocardial metabolism in the immediate period following global heart hypoxia.

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Coronary Disease; Disease Models, Animal; Female; Glucose; Glycogen; Heart; Hemodynamics; Hypoxia; Lactates; Male; Myocardial Revascularization; Myocardium; Oxygen Consumption; Phosphocreatine; Swine

The effect of ischemia on synthesis of myocardial proteins was investigated using a model of perfusion in which low levels of coronary flow were provided to paced hearts worked against a closed aortic outflow tract. These conditions rapidly produced ischemia and ventricular failure, as evidence by reduced coronary flow, increased left atrial pressure, and decreased pressure development. Protein synthesis was inhibited in a subsequent 1-hour period, during which a minimal coronary flow was maintained by retrograde perfusion. ATP, GTP, and creatinine phosphate were depleted in ischemic hearts and AMP accumulated. Production and accumulation of lactate within the tissue increased, whereas palmitate uptake was inhibited. The inhibition of protein synthesis was not associated with reduced levels of intracellular amino acids. During ischemia, decreased levels of ribosomal subunits as compared to paced or unpaced aerobic hearts suggested that peptide chain elongation was slow relative to initiation. Provision of insulin further reduced subunit levels but did not increase protein synthesis, suggesting that the hormone did not prevent inhibition of peptide chain elongation in energy-poor hearts.

Topics: Aerobiosis; Anaerobiosis; Animals; Coronary Circulation; Coronary Disease; Disease Models, Animal; Hypoxia; Lactates; Male; Muscle Proteins; Myocardium; Perfusion; Phenylalanine; Phosphocreatine; Purine Nucleotides; Rats

Topics: Adenosine Triphosphate; Animals; Coronary Disease; Depression, Chemical; Disease Models, Animal; Dogs; Glucosephosphates; Glycogen; Glycolysis; Heart; Lactates; Myocardium; Nitroglycerin; Phosphocreatine; Phosphorylases

After establishing a model of ischemia, perfusion in the ischemic area was considerably disturbed. Examination by means of 133xenon-clearance after intramyocardiac injection showed strongly delayed flowing-off compared with controls. Counterpulsation accelerates the flowing-off (perfusion). Untreated control animals reveal after inducing the model ischemia a crucial decrease of ATP concentration and an excessive increase of lactate concentration in the ischemic area. Counterpulsation may inhibit further decrease of ATP in the ischemic area.

Topics: Adenosine Triphosphate; Animals; Assisted Circulation; Coronary Disease; Disease Models, Animal; Humans; Intra-Aortic Balloon Pumping; L-Lactate Dehydrogenase; Lactates; Ligation; Metabolic Clearance Rate; Myocardium; Perfusion; Phosphocreatine; Time Factors; Xenon Radioisotopes

Intracoronary injection of 14 mcg. of tetrodotoxin into the ischemic isolated rat heart resulted in immediate cessation of mechanical activity. Upon reperfusion with oxygenated, modified Krebs-Henseleit bicarbonate buffer in a modified Langendorff apparatus, all hearts recovered normal rate, rtythm, and contractile vigor after up to 60 minutes of ischemia. In contrast, all hearts not administered tetrodotoxin showed bradycardia, irregular rhythm, and weak contraction upon reperfusion after 30 and 45 minutes of ischemia; after 60 minutes, no mechanical activity was evident. The improved cardiac function following ischemia in the tetrodotoxin-treated hearts was associated with persistence of normal adenosine triphosphate (ATP) levels after up to 30 minutes of ischemia and normal or elevated creatine phosphate (CP) levels after up to 60 minutes of ischemia. On the other hand, ATP and CP levels progressively declined to reach 50 per cent of normal values after 30 minutes in the ischemic hearts without tetrodotoxin. These findings indicate that postarrest ATP and CP levels play an important role in myocardial recovery after ischemic arrest.

Topics: Adenosine Triphosphate; Animals; Bicarbonates; Buffers; Coronary Disease; Disease Models, Animal; Heart; Heart Arrest; Heart Conduction System; Heart Rate; Myocardium; Perfusion; Phosphocreatine; Rats; Tetrodotoxin; Time Factors

Adult rhesus monkeys were subjected to complete cerebral ischemia for one hour and subsequent recirculation for up to 24 h. Animals with signs of functional recovery (e.g. spontaneous EEG activity) exhibited a partial replenishment of cellular energy sources (ATP, phosphocreatine) and a progressive normalization of cerebral lactate levels. Glucose and pyruvate concentrations showed a transient increase over control values during the early stages of postischemic recirculation. Monkeys without functional recovery lacked a significant resynthesis of energy-rich compounds; adenine nucleotides continued to decrease and lactate concentrations were higher than in animals subjected to ischemia without recirculation. Cerebral polysome profiles remained unaltered during the ischemic period but in all animals a marked disaggregation of polyribosomes with a concomitant increase in ribosomal subunits occurred after the onset of recirculation. In monkeys with indications of functional recovery these changes were reversible but a normal polysome profile was only observed after 24 h of recirculation. The results obtained indicate a postischemic depression of protein synthesis due to an inhibition of peptide chain initiation. After recirculation of the brain for 3-6 h there was evidence for an induction of enzymes involved in polyamine synthesis (ornithine decarboxylase and S-adenosylmethionine decarboxylase). No changes in the activity of these enzymes were observed at the end of the ischemic period, indicating that during complete cerebral ischemia not only the synthesis but also the catabolism of proteins is inhibited.

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Adenosylmethionine Decarboxylase; Animals; Brain; Cerebrovascular Circulation; Disease Models, Animal; Electroencephalography; Energy Metabolism; Female; Glucose; Ischemic Attack, Transient; Lactates; Macaca mulatta; Male; Nerve Tissue Proteins; Ornithine Decarboxylase; Phosphocreatine; Polyribosomes; Pyruvates; Time Factors

After experimental ureterotomy in mice, the changes which occurred in cerebral metabolism were studied. A significant increase in the cerebral glucose and glycogen level as well as of degradation power was noticed 25 hours after the operation. The level of lactic acid production in the same period of renal insufficience indicated a gradual decreasing tendency. These results as well as further details are discussed with regard to the underlying disturbances.

Topics: Acute Kidney Injury; Adenosine Triphosphate; Animals; Anuria; Brain; Disease Models, Animal; Energy Metabolism; Glucose; Glycogen; Lactates; Male; Mice; Phosphocreatine; Time Factors; Urea

After local complete ischemia at normothermia of 60, 100, 140, and 180 min duration the status of the adenylic acid-creatine phosphate system in the canine myocardium recovered to 98, 85, 74, and 30 percent of the control values, whereas glycogen was restored even more. In the infarcted myocardium the extent of alterations of the metabolic status was a function of the residual blood flow. Deviations from a regular metabolic status developed if the blood flow dropped below about 35 ml/min/100 gm. This critical flow rate is expected to vary with the energy requirement of the heart, but it is in keeping with results obtained by Rudolph and coworkers (personal communication) who found that patients with a myocardial blood flow below 30 ml/min/100 gm had a life expectancy of less than 1 month. In the nonaffected myocardium, both in experiments with local complete ischemia and in experiments with infarction, the metabolic status was always within normal ranges. This is in contrast to results published by Gudbjarnason (1971/1972) and Gudbjarnason, Puri, and Mathes (1971), who found that in noninfarcted myocardium tissue levels of ATP and creatine phosphate decreased to about 50 percent of the control values and that there was no restoration to normal values within 10 days after infarction.

Topics: Adenosine Monophosphate; Animals; Coronary Disease; Creatine; Disease Models, Animal; Dogs; Glycogen; Heart Ventricles; Lactates; Myocardial Infarction; Myocardium; Phosphocreatine; Time Factors

The effect of prolonged adminstration of ehtanol on cardiac metabolism, contractility, and ultrastructure was investigated. Dogs received 400 ml of a 25 percent solution of ethanol during a period of 3-6 months. Repeated heart muscle biopsied revealed a significant diminution in the activity of intramitochondrial NAD-linked isocitrate dehydrogenase in the animals exposed to alcohol. Oxidative, phosphorylation of mitochondria was measured polarographically using a vibrating oxygen electrode; respiratory control index and mitochondrial oxygen consumption were markedly reduced (p less than 0.001). Myocardial ATP content was significantly diminished (p less than 0.025). Electron microscopic changes observed consisted of mitochondrial degeneration, dehiscence of intercalated discs, and dilatation of intercellular spaces. The average force velocity curve was shifted downward and to the left in afterloaded contractions with a significant depression of Vmax (p less than 0.01). Both calcium binding and calcium uptake of mitochondria and sarcoplasmic reticulum were inhibited. These results suggest that a disorder in the generation of energy and a defect in calcium binding by subcellular membranes may be the determinant events leading to impaired myocardial function in the course of chronic alcoholism.

Topics: Adenine Nucleotides; Alcoholism; Animals; Binding Sites; Calcium; Cardiomyopathies; Disease Models, Animal; Dogs; Humans; Isocitrate Dehydrogenase; Mitochondria, Muscle; Myocardial Contraction; Myocardium; Oxygen Consumption; Phosphocreatine; Sarcoplasmic Reticulum

Topics: Acid-Base Equilibrium; Adenosine; Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Amino Acids; Ammonia; Animals; Aspartic Acid; Brain; Carbohydrate Metabolism; Carbon Dioxide; Citrates; Disease Models, Animal; Glucose; Glutamates; Glutamine; Hydrogen-Ion Concentration; Intracranial Pressure; Ischemic Attack, Transient; Ketoglutaric Acids; Lactates; Malates; Nucleotidases; Oxidation-Reduction; Partial Pressure; Phosphocreatine; Pyruvates; Rats

Topics: Adenosine; Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Amino Acids; Ammonia; Animals; Aspartic Acid; Blood Pressure; Carbohydrate Metabolism; Carbon Dioxide; Cerebral Cortex; Citric Acid Cycle; Disease Models, Animal; Electroencephalography; Glucose; Glutamine; Hydrogen-Ion Concentration; Intracranial Pressure; Ischemic Attack, Transient; Ketoglutaric Acids; Lactates; Malates; Mitochondria; Nucleotidases; Oxygen; Partial Pressure; Phosphocreatine; Pyruvates; Rats; Time Factors

Topics: Adenosine Triphosphatases; Adenosine Triphosphate; Animals; Cholesterol; Disease Models, Animal; Energy Metabolism; L-Lactate Dehydrogenase; Myocardial Infarction; Phosphocreatine; Phospholipids; Rabbits; Succinate Dehydrogenase; Testosterone; Transaminases

Topics: Adenosine Triphosphate; Altitude; Animals; Body Weight; Cardiomegaly; Disease Models, Animal; Heart Ventricles; Hypoxia; Organ Size; Phosphocreatine; Rats; Time Factors

Topics: Adenine Nucleotides; Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Coronary Circulation; Coronary Disease; Disease Models, Animal; Heart; Heart Failure; Lactates; Male; Myocardium; Oxygen Consumption; Phosphocreatine; Rats; Regional Blood Flow; Time Factors

Topics: Acidosis; Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Brain; Brain Chemistry; Carbon Dioxide; Cerebrovascular Circulation; Disease Models, Animal; Glucosephosphates; Hypoxia; Hypoxia, Brain; Ischemic Attack, Transient; Keto Acids; Lactates; Ligation; Malates; Nitrogen; Oxygen; Oxygen Consumption; Partial Pressure; Phosphocreatine; Rats

Topics: Adenosine Triphosphate; Animals; Brain; Carbon Dioxide; Cerebrovascular Circulation; Disease Models, Animal; Electric Stimulation; Electroencephalography; Electroshock; Energy Metabolism; Evoked Potentials; Lactates; Oxygen; Oxygen Consumption; Partial Pressure; Pentylenetetrazole; Phosphocreatine; Rats; Seizures

Topics: Acute Disease; Adenine Nucleotides; Aerobiosis; Anaerobiosis; Animals; Coronary Disease; Coronary Vessels; Disease Models, Animal; Dogs; Fatty Acids; Glucose; Glycolysis; Hydrogen-Ion Concentration; Lactates; Mitochondria, Muscle; Models, Biological; Myocardial Infarction; Myocardium; Phosphocreatine

Topics: Adenosine Triphosphate; Animals; Argon; Cochlea; Cochlear Nerve; Disease Models, Animal; Ear, Inner; Electrophysiology; Freeze Drying; Glucose; Glycogen; Guinea Pigs; Ischemia; Labyrinth Diseases; Labyrinthine Fluids; Lactates; Organ of Corti; Phosphocreatine; Time Factors; Vestibule, Labyrinth

Topics: Acute Disease; Adenosine Triphosphate; Animals; Coronary Disease; Coronary Vessels; Disease Models, Animal; Dogs; Lactates; Myocardial Infarction; Myocardium; Phosphocreatine; Time Factors

Topics: Acid Phosphatase; Adenosine Diphosphate; Adenosine Triphosphate; Anabolic Agents; Animals; Disease Models, Animal; Dogs; Glucuronidase; Heart; Heart Ventricles; Lactates; Myocardial Contraction; Myocardial Infarction; Myocardium; Norepinephrine; Phosphocreatine; Proline; Pyruvates; Time Factors

Topics: Adenine Nucleotides; Animals; Asphyxia; Cardiomegaly; Cricetinae; Disease Models, Animal; Energy Metabolism; Heart Failure; Mesocricetus; Phosphocreatine; Rats

Topics: Acid-Base Equilibrium; Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Bicarbonates; Brain; Carbon Dioxide; Disease Models, Animal; Hemoglobins; Hepatectomy; Hepatic Encephalopathy; Hydrogen-Ion Concentration; Lactates; Male; NAD; Oxygen; Partial Pressure; Phosphocreatine; Pyruvates; Rats

Topics: Adenosine Triphosphate; Animals; Brain Neoplasms; Disease Models, Animal; Fluorometry; Freezing; Glioblastoma; Glucose; Glycogen; Histocytochemistry; Lactates; Mice; NAD; NADP; Neoplasm Transplantation; Neoplasms, Experimental; Neuroglia; Oxygen Consumption; Pentoses; Phosphates; Phosphocreatine; Transplantation, Homologous

Topics: Adenine Nucleotides; Animals; Brain; Brain Chemistry; Disease Models, Animal; Hypoxia; Lactates; NAD; NADP; Oxygen; Oxygen Consumption; Partial Pressure; Phosphocreatine; Pyruvates; Rats

Topics: Adenosine Triphosphate; Animals; Blood Pressure; Cardiac Output; Chronic Disease; Creatine; Disease Models, Animal; Dogs; Elasticity; Heart; Heart Failure; Heart Rate; Heart Ventricles; Muscle Contraction; Myocardium; Oxygen Consumption; Pacemaker, Artificial; Phosphocreatine; Statistics as Topic; Tachycardia

Topics: Adenosine Diphosphate; Adenosine Triphosphate; Animals; Biopsy; Carbon Isotopes; Coronary Vessels; Disease Models, Animal; Dogs; Heart Ventricles; Hemodynamics; Hydroxyproline; Lactates; Ligation; Myocardial Infarction; Myocardium; Norepinephrine; Oxygen Consumption; Phosphocreatine; Pyruvates; Time Factors; Water

Topics: Acidosis; Adenosine Triphosphatases; Adenosine Triphosphate; Amino Acids; Animals; Blood Glucose; Blood Pressure; Blood Proteins; Blood Transfusion; Blood Volume; Disease Models, Animal; Dogs; Fructose; Glycogen; Hydrogen-Ion Concentration; Hyperbaric Oxygenation; Hypotension; Lactates; Methods; Phosphates; Phosphocreatine; Pulse; Pyruvates; Respiration

Topics: Adenosine Triphosphate; Anesthesia; Animals; Centrifugation; Cerebral Cortex; Disease Models, Animal; Fluorometry; Glucose; Glycogen; Ischemic Attack, Transient; Lipid Metabolism; Male; Mice; Phosphates; Phosphocreatine

Topics: Acetylcholinesterase; Adenosine Triphosphate; Amino Acids; Aminobutyrates; Animals; Brain; Chromatography, Paper; Disease Models, Animal; Glucose; Glycogen; Lactates; Oxygen Consumption; Phosphates; Phosphocreatine; Plant Extracts; Propionates; Rats; Seizures; Toxins, Biological

Topics: Adaptation, Physiological; Altitude; Animals; Aortic Coarctation; Cerebral Cortex; Disease Models, Animal; Glycogen; Heart; Heart Failure; Hypoxia; Methods; Muscle Contraction; Myocardium; Phosphocreatine; Protein Biosynthesis; Rats; RNA

Topics: Adenine Nucleotides; Adenosine Triphosphate; Animals; Cardiomyopathies; Diet; Disease Models, Animal; Heart Failure; Microscopy, Electron; Mitochondria, Muscle; Myocardium; Norepinephrine; Oxygen Consumption; Phosphocreatine; Rabbits; Rats