phosphocreatine and Ischemia

Topics: Adenine Nucleotides; Aerobiosis; Anaerobiosis; Animals; Asphyxia; Cold Temperature; Coronary Disease; Dogs; Glycolysis; Heart Arrest; Homeostasis; Hypoxia; Ischemia; Myocardium; Oxygen Consumption; Phosphocreatine

Topics: Adenosine Triphosphate; Animals; Blood Pressure; Brain; Brain Chemistry; Brain Damage, Chronic; Brain Edema; Carbon Dioxide; Cats; Cerebrovascular Circulation; Cerebrovascular Disorders; Electroencephalography; Heart Arrest; Humans; Hypotension; Hypoxia; Hypoxia, Brain; Indicator Dilution Techniques; Ischemia; Lactates; Mathematics; Oxygen; Phosphocreatine; Prognosis; Vasomotor System

Topics: Adenosine Triphosphate; Animals; Calcium; Coronary Vessels; Glycolysis; Heart; Humans; Hypoxia; Ischemia; Muscle Contraction; Muscle Proteins; Myocardium; Oxidative Phosphorylation; Oxygen; Phosphocreatine

Topics: Animals; Dogs; Glucosyltransferases; Glycerophosphates; Glycolysis; Guinea Pigs; Hypoxia; Ischemia; Lactates; Myocardium; Phosphates; Phosphocreatine; Phosphorylase Kinase; Rabbits; Rats

Glutathione (GSH) is an important endogenous scavenger against reactive oxygen species. Elective abdominal surgery without ischemia and reperfusion leads to decreased muscle GSH concentrations 4-72 hr postoperatively without altering GSH redox status. In the present study, we investigated to what extent muscle GSH status was affected during and following elective abdominal aortic aneurysm repair. From patients (n = 10) undergoing abdominal aortic repair, thigh muscle specimens were taken preoperatively, at maximal ischemia, and at 10 min and 4, 24, and 48 hr of reperfusion. Specimens were analyzed for GSH, amino acids, and energy-rich compounds. At maximal ischemia, phosphocreatine decreased by 37% (p < 0.05) and lactate and creatine increased by 274% and 57% (p < 0.001 and 0.05), respectively, indicating ischemia during the clamping of aorta. Adenosine triphosphate, on the other hand, remained unaltered during the entire study period. Total GSH (tGSH) decreased by 46% at 24 hr and by 43% at 48 hr of reperfusion (p < 0.001), while reduced GSH decreased by 48% at 24 hr and by 44% at 48 hr (p < 0.001). The redox status (GSH/tGSH) of GSH and oxidized GSH remained unaltered. Among the constituent amino acids of GSH, glycine and cysteine remained unaltered while glutamine and glutamate decreased by 55% and 55%, respectively (p < 0.001). Abdominal aortic aneurysm repair induces metabolic alterations characteristic for ischemia. The antioxidative capacity in terms of muscle levels of GSH was decreased. However, the oxidative stress during reperfusion did not change GSH status more than what has been reported following abdominal surgery without ischemia and reperfusion. The results indicate that the oxidative stress elicited by elective abdominal aortic aneurysm repair is outbalanced by a compensated GSH metabolism not giving rise to an increased amount of oxidized GSH or an altered GSH redox status.

Topics: Aged; Aged, 80 and over; Aortic Aneurysm, Abdominal; Elective Surgical Procedures; Female; Glutamine; Glutathione; Humans; Ischemia; Lactic Acid; Leg; Male; Muscle, Skeletal; Phosphocreatine; Reperfusion; Time Factors

Skeletal muscle voluntary contractions (VC) and electrical stimulations (ES) were compared in eight healthy men. High-energy phosphates and myoglobin oxygenation were simultaneously monitored in the quadriceps by interleaved (1)H- and (31)P-NMR spectroscopy. For the VC protocol, subjects performed five or six bouts of 5 min with a workload increment of 10% of maximal voluntary torque (MVT) at each step. The ES protocol consisted of a 13-min exercise with a load corresponding to 10% MVT. For both protocols, exercise consisted of 6-s isometric contractions and 6-s rest cycles. For an identical mechanical level (10% MVT), ES induced larger changes than VC in the P(i)-to-phosphocreatine ratio [1.38 +/- 1.14 (ES) vs. 0.13 +/- 0.04 (VC)], pH [6.69 +/- 0.11 (ES) vs. 7.04 +/- 0.07 (VC)] and myoglobin desaturation [43 +/- 15.9 (ES) vs. 6.1 +/- 4.6% (VC)]. ES activated the muscle facing the NMR coil to a greater extent than did VCs when evaluated under identical technical conditions. This metabolic pattern can be interpreted in terms of specific temporal and spatial muscle cell recruitment. Furthermore, at identical levels of energy charge, the muscle was more acidotic and cytoplasm appeared more oxygenated during ES than during VC. These results are in accordance with a preferential recruitment of type II fibers and a relative muscle hyperperfusion during ES.

Topics: Adenosine Diphosphate; Adenosine Triphosphate; Adult; Electric Stimulation; Energy Metabolism; Exercise; Glycolysis; Humans; Hydrogen-Ion Concentration; Ischemia; Isometric Contraction; Magnetic Resonance Spectroscopy; Male; Muscle Contraction; Muscle Fibers, Skeletal; Muscle, Skeletal; Myoglobin; Oxygen Consumption; Phosphocreatine; Recruitment, Neurophysiological

1. In ischaemic exercise ATP is supplied only by glycogenolysis and net splitting of phosphocreatine (PCr). Furthermore, 'proton balance' involves only glycolytic lactate/H+ generation and net H+ 'consumption' by PCr splitting. This work examines the interplay between these, metabolic regulation and the creatine kinase equilibrium. 2. Nine male subjects (age 25-45 years) performed finger flexion (7 % maximal voluntary contraction at 0.67 Hz) under cuff ischaemia. 31P magnetic resonance spectra were acquired from finger flexor muscle in a 4.7 T magnet using a 5 cm surface coil. 3. Initial PCr depletion rate estimates total ATP turnover rate; glycolytic ATP synthesis was obtained from this and changes in [PCr], and then used to obtain flux through 'distal' glycolysis (phosphofructokinase and beyond) to lactate; 'proximal' flux (through phosphorylase) was obtained from this and changes in [phosphomonoester]. Total H+ load (lactate load less H+ consumption) was used to estimate cytosolic buffer capacity (beta). 4. Glycolytic ATP synthesis increased from near zero while PCr splitting declined. Net H+ load was approximately linear with pH, suggesting beta = 20 mmol x l(-1) (pH unit)(-1) at rest, increasing as pH falls. 5. Relationships between glycolytic rate and changes in [PCr] (i.e. the time-integrated mismatch between ATP use and production), and thus also [P(i)] (substrate for phosphorylase), suggest that increase in glycolysis is due partly to 'open-loop' Ca2+-dependent conversion of phosphorylase b to a, and partly to the 'closed loop' increase in P(i) consequent on net PCr splitting. 6. The 'settings' of these mechanisms have a strong influence on changes in pH and metabolite concentrations.

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Adult; Algorithms; Cytosol; Exercise; Glycogen; Glycolysis; Humans; Hydrogen-Ion Concentration; Ischemia; Kinetics; Lactates; Magnetic Resonance Spectroscopy; Male; Middle Aged; Muscle, Skeletal; Phosphocreatine; Phosphofructokinases; Protons

Determining viability of tissues and wound-healing potential in diabetic patients remains a significant challenge. Current methods for preoperative assessment of wound-healing potential (pressures in the ankle, temperature of tissues, transcutaneous measurements of oxygen, and systemic nutritional status) are indirect, in that they characterize the delivery of oxygen or other nutrients to the cells. A noninvasive means to measure adenosine triphosphate (ATP) and phosphocreatine (PCr), the fundamental high energy phosphate substrates of oxidative energy-metabolism in the skin, has been devised by using magnetic resonance spectroscopy (MRS). The signal-to-noise ratio of bioenergetic metabolites in the skin was 86% lower in five patients with diabetes who had ischemia of the lower extremity compared with five control subjects (P < 0.0001), suggesting that the concentration of high energy metabolites in diabetic patients was reduced. The ratio of ATP/phosphocreatine (PCr) in patients with diabetes was also significantly lower than in controls (P < 0.01). Chewing a single piece of nicotine gum reduced the measured concentrations of ATP and PCr in control subjects by an average of 18% and by an average of 75% in subjects with diabetes. To verify these results in a second experiment, skin was harvested from the surgical wound sites in eight patients with diabetes undergoing elective amputation, eight patients with diabetes undergoing elective foot surgery, and ten age-matched control (nondiabetic) patients undergoing elective foot surgery. Analysis of ATP and PCr using high pressure liquid chromatography corroborated MRS findings, showing a significant reduction in ATP and PCr in diabetic skin. Depression of metabolites was more severe in the patients with diabetes undergoing amputation than in the ones undergoing elective surgery. Results demonstrate depression of metabolites in the skin of patients with diabetes and suggest that MRS with 31p may be useful in characterizing metabolites in the skin.

Topics: Adenosine Triphosphate; Adult; Chromatography, High Pressure Liquid; Diabetes Mellitus, Type 1; Diabetic Foot; Humans; Ischemia; Leg; Magnetic Resonance Spectroscopy; Middle Aged; Phosphocreatine; Phosphorus Isotopes; Risk Factors; Skin; Wound Healing

The rate of metabolism in forearm flexor muscles (MO2) was derived from near-infrared spectroscopy (NIRS-O2) during ischaemia at rest rhythmic handgrip at 15% and 30% of maximal voluntary contraction (MVC), post-exercise muscle ischaemia (PEMI), and recovery in seven subjects. The MO2 was compared with forearm oxygen uptake (VO2) [flow x (oxygen saturation in arnterial blood-oxygen saturation in venous blood, SaO2 - SvO2)], and with the 31P-magnetic resonance spectroscopy-determined ratio of inorganic phosphate to phosphocreatine (P(I):PCr). During ischaemia at rest, the fall in NIRS-O2 was more pronounced [76 (SEM 3) to 3 (SEM 1)%] than in SvO2 [71 (SEM 3) to 59 (SEM 2)%]. During the handgrip, NIRS-O2 was lower at 30% compared to 15% MVC [58 (SEM 3) v.s. 67 (SEM 3)%] while the SvO2 was similar [29 (SEM 3) v.s. 31 (SEM 4)%]. Accordingly, MO2 as well as P(I):PCr increased twofold, while VO2 increased only 30%. During PEMI after 15% and 30% MVC, NIRS-O2 fell to 9 (SEM 1)% and "0", but the use of oxygen by forearm muscles was not reflected in SvO2. During reperfusion after PEMI, the peak NIRS-O2 was lowest after intense exercise, while for SvO2 the reverse was seen. The discrepancies between NIRS-O2 and SvO2, and therefore between the estimates of the metabolic rate, would suggest significant limitations in sampling venous blood which is representative of the flexor muscle capillaries. In support of this contention, SvO2 and venous pH decreased during the first seconds of reperfusion after PEMI. To conclude, NIRS-O2 of forearm flexor muscles closely reflected the exercise intensity and the metabolic rate determined by magnetic resonance spectroscopy but not that rate derived from flow and the arterio-venous oxygen difference.

Topics: Adult; Blood Gas Analysis; Capillaries; Female; Hand Strength; Humans; Hydrogen-Ion Concentration; Ischemia; Magnetic Resonance Spectroscopy; Male; Muscle Contraction; Muscle, Skeletal; Oxygen Consumption; Phosphates; Phosphocreatine; Regional Blood Flow; Spectroscopy, Near-Infrared

We have used 31phosphorus magnetic resonance spectroscopy (31P-MRS) to study foot muscle metabolism in patients with peripheral vascular disease. Sixteen patients with calf claudication, 32 patients with rest pain and 13 control subjects had spectra collected from the foot muscle, Extensor digitorum brevis, ankle pressures measured and, in most cases, transcutaneous O2 and CO2 recordings made over the foot. The intracellular pH and the ratio of inorganic phosphate to phosphocreatine (Pi/PCr) obtained from the MR spectra were significantly higher (p less than 0.005 and p less than 0.02, respectively) in the muscle of patients with rest pain and were particularly high in those with gangrene or ulceration. Ankle pressures and transcutaneous O2 and CO2 measurements failed to distinguish those patients with advanced peripheral ischaemia. These results suggest that MRS measurements of metabolic changes in foot muscle are useful in the detection and quantitation of significant distal ischaemia.

Topics: Aged; Blood Gas Monitoring, Transcutaneous; Female; Foot; Humans; Intermittent Claudication; Ischemia; Magnetic Resonance Spectroscopy; Male; Muscles; Phosphates; Phosphocreatine

Increases in muscle size and strength similar to those obtained with high resistance load can be achieved by combining lower loads with continuous blood flow restriction (BFR). However, high ratings for distress have been reported for continuous BFR. Therefore, we investigated the efficacy (metabolic stress) of BFR applied only during intervals in resistance exercise. Seven healthy men performed three 1-min sets of plantar flexion (30 reps/min) with 1-min rest intervals under 4 conditions: low-load resistance exercise (L, 20% 1-repetition maximum (1RM)) without BFR (L-noBFR), L with BFR during exercise sets (L-exBFR), L with BFR during rest intervals (L-intBFR), and L with continuous BFR during both exercise and rest intervals (L-conBFR). Based on the results of the first experiment, we performed additional protocols using a moderate load (M, 40% 1RM) with intermittent (exercise or rest intervals) BFR (M-exBFR and M-intBFR). Intramuscular metabolic stress, defined as decreases in phosphocreatine and intramuscular pH, was evaluated by

Topics: Blood Pressure; Humans; Hydrogen-Ion Concentration; Ischemia; Magnetic Resonance Spectroscopy; Male; Muscle, Skeletal; Phosphocreatine; Regional Blood Flow; Resistance Training; Stress, Physiological; Young Adult

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

Sickle cell disease (SCD) is characterized by painful vaso-occlusive crisis. While there are several metabolic abnormalities potentially associated with muscular ischemia-reperfusion cycles that could be harmful in the context of SCD, the metabolic consequences of such events are still unknown. Ten controls (HbAA), thirteen heterozygous (HbAS), and ten homozygous (HbSS) SCD mice were submitted to a standardized protocol of rest-ischemia-reperfusion of the left leg during which adenosine triphosphate, phosphocreatine, and inorganic phosphate concentrations as well as intramuscular pH were measured using phosphorous magnetic resonance spectroscopy (MRS). Forty-eight hours later, skeletal muscles were harvested. Oxidative stress markers were then measured on the tibialis anterior. At the end of the ischemic period, HbSS mice had a lower pH value as compared with the HbAA and HbAS groups (

Topics: Acute Disease; Adenosine Triphosphate; Anemia, Sickle Cell; Animals; Antioxidants; Hydrogen-Ion Concentration; Ischemia; Magnetic Resonance Spectroscopy; Mice; Muscle, Skeletal; Oxidative Stress; Phosphocreatine; Reperfusion Injury; Rest; Time Factors

Ischemia-reperfusion injury is a devastating complication that occurs in allotransplantation and replantation of limbs. Over the years, several preservation strategies have been used to conserve the critical levels of intracellular adenosine triphosphate (ATP) during ischemia to sustain the ion gradients across the membranes and thus the tissue viability. The administration of exogenous ATP to ischemic tissues is known to provide beneficial effects during reperfusion, but it is unclear whether it provides protection during ischemia. The purpose of the present study was to determine the effect of ATP administration on high-energy phosphate levels in ischemic skeletal muscle and to examine the role of purinergic and adenosine receptors in mediating the response to exogenous ATP.. The extensor digitorum longus muscles of Fischer rats were subjected to ischemia and treated with different concentrations of ATP with or without purinergic and adenosine receptor blockers. Phosphorus-31 nuclear magnetic resonance spectroscopy was used to measure the rate of decay of ATP, phosphocreatine (PCr), and the formation of adenosine monophosphate and acidification. Phosphorylated compounds were analyzed using a simple model of energy metabolism, and the PCr half-life was used as an index of internal depletion of ATP to distinguish between intracellular and extracellular ATP.. PCr decay was rapid in all muscle groups and was followed by gradual ATP decay. The half-life of PCr was significantly longer in the ATP-treated muscles than in the vehicle controls and was maximally prolonged by treating with slow hydrolyzing adenosine 5'-O-(3-thio)triphosphate. Purinoceptor (P2X) blockade with ATP treatment significantly increased the half-life of PCr, and adenosine receptor blockers blunted the response. Administration of adenosine to ischemic muscles significantly increased the half-life of PCr compared with that in the vehicle controls.. Exogenous ATP administration to ischemic skeletal muscles appears to spare intracellular energy by acting primarily through adenosine receptors.

Topics: Adenosine Triphosphate; Animals; Energy Metabolism; Ischemia; Male; Muscle, Skeletal; Phosphocreatine; Rats; Rats, Inbred F344; Receptors, Purinergic P1

The hypothesis was tested that the variation of in vivo glycolytic flux with contraction frequency in skeletal muscle can be qualitatively and quantitatively explained by calcium-calmodulin activation of phosphofructokinase (PFK-1). Ischemic rat tibialis anterior muscle was electrically stimulated at frequencies between 0 and 80 Hz to covary the ATP turnover rate and calcium concentration in the tissue. Estimates of in vivo glycolytic rates and cellular free energetic states were derived from dynamic changes in intramuscular pH and phosphocreatine content, respectively, determined by phosphorus magnetic resonance spectroscopy ((31)P-MRS). Computational modeling was applied to relate these empirical observations to understanding of the biochemistry of muscle glycolysis. Hereto, the kinetic model of PFK activity in a previously reported mathematical model of the glycolytic pathway (Vinnakota KC, Rusk J, Palmer L, Shankland E, Kushmerick MJ. J Physiol 588: 1961-1983, 2010) was adapted to contain a calcium-calmodulin binding sensitivity. The two main results were introduction of regulation of PFK-1 activity by binding of a calcium-calmodulin complex in combination with activation by increased concentrations of AMP and ADP was essential to qualitatively and quantitatively explain the experimental observations. Secondly, the model predicted that shutdown of glycolytic ATP production flux in muscle postexercise may lag behind deactivation of PFK-1 (timescales: 5-10 s vs. 100-200 ms, respectively) as a result of accumulation of glycolytic intermediates downstream of PFK during contractions.

Topics: Adenosine Triphosphate; Animals; Calcium; Calmodulin; Computer Simulation; Glycolysis; Hydrogen-Ion Concentration; Ischemia; Magnetic Resonance Spectroscopy; Male; Models, Biological; Muscle Contraction; Muscle, Skeletal; Phosphocreatine; Phosphofructokinase-1, Muscle Type; Physical Conditioning, Animal; Rats; Rats, Wistar

We hypothesized that pretreatment with single-dose cyclosporine (CsA) prevents alterations and improves tissue oxygen and mitochondrial cytochrome oxidase redox (CytOx) state in skeletal muscle ischemia and reperfusion-reoxygenation (I/R). Latissimus dorsi muscle was prepared and mobilized in New Zealand white rabbits. Ischemia was induced for 4 h, followed by 2 h of reperfusion. The animals were randomized to receive a 60-mg/kg intravenous bolus of CsA (CsA group, n = 10) or physiologic saline (control, n = 10) at 10 min before ischemia onset. Muscle tissue oxygen tension (PtO(2)) and mitochondrial CytOx were measured during I/R simultaneously. High-energy phosphate (HEP) levels were determined using high-field (31)P magnetic resonance spectroscopy. Mitochondrial viability index and wet-to-dry ratio were used to assess the tissue viability between groups. Decreases in tissue oxygen levels and CytOx were slower during ischemia in the CsA group in comparison to control group, also the loss of phosphocreatine and adenosine triphosphate depletion. After ischemia, recovery of tissue oxygen, mitochondrial CytOx, and HEP was delayed in controls. Tissue PtO2 in the CsA group (P < 0.05) was significantly higher compared with that in the control group after I/R. Mitochondrial CytOx was also improved in the CsA group (P < 0.01 vs. control). Muscle HEP levels (phosphocreatine, adenosine triphosphate) were significantly preserved in the CsA group versus the control group (P < 0.01, P < 0.05). Mitochondrial viability index and wet-to-dry ratio confirmed significantly preserved tissue and lower edema formation in the CsA group. The pretreatment with single-dose CsA prevents alterations and improves tissue oxygenation and mitochondrial oxidation in skeletal muscle I/R.

Topics: Adenosine Triphosphate; Animals; Constriction; Cyclosporine; Edema; Electron Transport Complex IV; Enzyme Inhibitors; Ischemia; Male; Mitochondria, Muscle; Muscle, Skeletal; Oxygen; Phosphocreatine; Rabbits; Random Allocation; Reperfusion Injury; Tissue Survival

Alternate methods to quantify mitochondrial activity or function have been extensively used for studying insulin resistance and type 2 diabetes mellitus, namely saturation transfer and phosphocreatine (PCr) recovery. As these methods are in fact determining different parameters, this study aimed to compare saturation transfer results to PCr recovery measurements within the same group. Fifteen subjects underwent saturation transfer and ischemic exercise-recovery experiments. PCr decrease during ischemia (Q), induced by cuff inflation, served as an additional measure of resting ATP (adenosine triphosphate) production. ATP synthetic rate (fATP) measured by saturation transfer (0.234 ± 0.043 mM/s) was greater than (Q = 0.0077 ± 0.0011 mM/s), but correlated well with Q (r = 0.63 P = 0.013). Parameters of PCr recovery correlated well with fATP (Q(max,lin) : r = 0.71, P = 0.003, Q(max,ADP) : r = 0.66, P = 0.007) and Q (Q(max,lin) : r = 0.92, P = 0.000002, Q(max,ADP) : r = 0.76, P = 0.001). In conclusion, although saturation transfer yields higher ATP synthetic rates than PCr decrease during ischemia, their significant correlation indicates that fATP can be used as a marker of mitochondrial activity. The finding that both Q and fATP correlate with PCr recovery kinetics suggests that skeletal muscle with greater maximal aerobic ATP synthetic rates is also metabolically more active at rest. Magn Reson Med, 2011. © 2011 Wiley-Liss, Inc.

Topics: Adenosine Triphosphate; Adult; Biomarkers; Energy Metabolism; Exercise; Humans; Ischemia; Magnetic Resonance Spectroscopy; Male; Mitochondria, Muscle; Muscle, Skeletal; Phosphocreatine; Phosphorus Isotopes

In children with congenital heart disease, female sex has been linked to greater in-hospital mortality associated with low cardiac output, yet the reasons for this are unclear. Therefore, we examined whether newborn sex differences in the heart's metabolic response to ischemia exist. Left ventricular (LV) in vivo and ischemic biopsies of newborn male and female piglets were compared. Tissue ATP, creatine phosphate (CP), glycogen, anaerobic end-products lactate and hydrogen ion (H), and key regulatory enzymes were measured. Compared with males, newborn females displayed 14% lower ATP, 22% lower CP, and 32% lower glycogen reserves (p < 0.05) at baseline. During ischemia, newborn females accumulated 17% greater lactate and 40% greater H accumulation (p < 0.02), which was associated with earlier cessation of glycolysis and lower ischemic ATP levels (p < 0.02) compared with males. Newborn females demonstrated a greater ability to use their glycogen reserves, resulting in significantly lower (p < 0.003) glycogen levels throughout the ischemic period. Thus, newborn females are at a metabolic disadvantage because they exhibited lower energy levels and greater tissue lactic acidosis, both linked to an increase susceptibility to ischemic injury and impair myocardial function on reperfusion.

Topics: Adenosine Triphosphate; Analysis of Variance; Animals; Animals, Newborn; Energy Metabolism; Female; Fluorometry; Glycogen; Heart Ventricles; Ischemia; Lactic Acid; Male; Myocardium; Phosphocreatine; Protons; Sex Factors; Sus scrofa

During ischemia and some types of muscular contractions, oxygen tension (Po(2)) declines to the point that mitochondrial ATP synthesis becomes limited by oxygen availability. Although this critical Po(2) has been determined in animal tissue in vitro and in situ, there remains controversy concerning potential disparities between values measured in vivo and ex vivo. To address this issue, we used concurrent heteronuclear magnetic resonance spectroscopy (MRS) to determine the critical intracellular Po(2) in resting human skeletal muscle in vivo. We interleaved measurements of deoxymyoglobin using (1)H-MRS with measures of high-energy phosphates and pH using (31)P-MRS, during 15 min of ischemia in the tibialis anterior muscles of 6 young men. ATP production and intramyocellular Po(2) were quantified throughout ischemia. Critical Po(2), determined as the Po(2) corresponding to the point where PCr begins to decline (PCr(ip)) in resting muscle during ischemia, was 0.35 ± 0.20 Torr, means ± SD. This in vivo value is consistent with reported values ex vivo and does not support the notion that critical Po(2) in resting muscle is higher when measured in vivo. Furthermore, we observed a 4.5-fold range of critical Po(2) values among the individuals studied. Regression analyses revealed that time to PCr(ip) was associated with critical Po(2) and the rate of myoglobin desaturation (r = 0.83, P = 0.04) but not the rate of ATP consumption during ischemia. The apparent dissociation between ATP demand and myoglobin deoxygenation during ischemia suggests that some degree of uncoupling between intracellular energetics and oxygenation is a potentially important factor that influences critical Po(2) in vivo.

Topics: Adenosine Triphosphate; Adult; Energy Metabolism; Humans; Hydrogen-Ion Concentration; Ischemia; Magnetic Resonance Spectroscopy; Male; Mitochondria, Muscle; Muscle, Skeletal; Myoglobin; Oxidative Phosphorylation; Oxygen; Phosphocreatine; Rest; Time Factors

Vibration training is commonly expected to induce an active muscle contraction via a complex reflex mechanism. In calf muscles of 20 untrained subjects, the additional energy consumption in response to vibration superimposed on an isometric contraction was examined by (31)P magnetic resonance spectroscopy and by near infrared spectroscopy. Subjects performed 3 min of isometric plantar flexion exercise at 40% MVC under four conditions: with (VIB) and without (CON) superimposed 20 Hz vibration at +/-2 mm amplitude, both combined with or without arterial occlusion (AO). After contraction under all conditions, the decreases in oxygenated haemoglobin were not significantly different. After VIB + AO consumption of ATP was increased by 60% over CON + AO, visible by significant decreases in [PCr] and intracellular pH (P < 0.05). The additional energy consumption by vibration was not detectable under natural perfusion. Probably without AO the additional energy consumption by vibration was compensated by oxidative phosphorylation enabled by additional perfusion.

Topics: Adenosine Triphosphate; Energy Metabolism; Humans; Hydrogen-Ion Concentration; Ischemia; Isometric Contraction; Leg; Magnetic Resonance Spectroscopy; Mitochondria, Muscle; Muscle, Skeletal; Oxygen Consumption; Oxyhemoglobins; Phosphocreatine; Phosphorylation; Spectroscopy, Near-Infrared; Vibration; Young Adult

Effect of 3-nitropropionic acid (3-NPA) and ischemia (glucose- and O(2)-free solution) on synaptic transmission in hemisected spinal cord from 4 to 8 day old rats was examined in vitro. Stimulation of a dorsal root (L3-5 segments) evoked monosynaptic (MSR) and polysynaptic reflex (PSR) potentials in the segmental ventral root. Superfusion of 3-NPA (0.17-3.4 mM) depressed the reflexes in a concentration- and time-dependent manner. At 3.4 mM of 3-NPA, the reflexes were abolished by 35 min. Time required to produce 50% depression (T-50) was around 170, 80, 40 and 17 min for MSR and 110, 70, 25 and 16 min for PSR at 0.17, 0.51, 1.7 and 3.4mM of 3-NPA, respectively. Ischemia also produced a time-dependent depression of reflexes and abolished them by 35 min and the T-50 values were around 18 min. Presence of creatine phosphate (10mM) in the superfusing medium did not alter the time course of 3-NPA-induced depression of reflexes but prolonged the ischemia-induced depression. dl-2-amino-5-phosphonovaleric acid (NMDA receptor antagonist; 10 microM) failed to block the 3-NPA (3.4 mM)-induced depression of reflexes, but blocked the ischemia-induced depression. The results indicate that 3-NPA-induced depression of spinal reflexes does not involve NMDA receptors and is different from ischemia-induced depression.

Topics: 2-Amino-5-phosphonovalerate; Action Potentials; Analysis of Variance; Animals; Animals, Newborn; Convulsants; Dose-Response Relationship, Drug; Excitatory Amino Acid Antagonists; Female; Glucose; In Vitro Techniques; Ischemia; Male; Neural Inhibition; Nitro Compounds; Phosphocreatine; Propionates; Rats; Reflex; Reflex, Monosynaptic; Spinal Cord; Spinal Nerve Roots; Synaptic Transmission; Time Factors

Muscle disuse induces a wide array of structural, biochemical, and neural adaptations in skeletal muscle, which can affect its function. We recently demonstrated in patients with an orthopedic injury that cast immobilization alters the resting P(i) content of skeletal muscle, which may contribute to loss of specific force. The goal of this study was to determine the direct effect of disuse on the basal phosphate content in skeletal muscle in an animal model, avoiding the confounding effects of injury/surgery. (31)P and (1)H MRS data were acquired from the gastrocnemius muscle of young adult mice (C57BL6 female, n = 8), at rest and during a reversible ischemia experiment, before and after 2 weeks of cast immobilization. Cast immobilization resulted in an increase in resting P(i) content (75%; p < 0.001) and the P(i) to phosphocreatine (PCr) ratio (P(i)/PCr; 80%, p < 0.001). The resting concentrations of ATP, PCr and total creatine (PCr + creatine) and the intracellular pH were not significantly different after immobilization. During ischemia (30 min), PCr concentrations decreased to 54 +/- 2% and 52 +/- 6% of the resting values in pre-immobilized and immobilized muscles, respectively, but there were no detectable differences in the rates of P(i) increase or PCr depletion (0.55 +/- 0.01 mM min(-1) and 0.52 +/- 0.03 mM min(-1) before and after immobilization, respectively; p = 0.78). At the end of ischemia, immobilized muscles had a twofold higher phosphorylation potential ([ADP][P(i)]/[ATP]) and intracellular buffering capacity (3.38 +/- 0.54 slykes vs 6.18 +/- 0.57 slykes). However, the rate of PCr resynthesis (k(PCr)) after ischemia, a measure of in vivo mitochondrial function, was significantly lower in the immobilized muscles (0.31 +/- 0.04 min(-1)) than in pre-immobilized muscles (0.43 +/- 0.04 min(-1)). In conclusion, our findings indicate that 2 weeks of cast immobilization, independent of injury-related alterations, leads to a significant increase in the resting P(i) content of mouse skeletal muscle. The increase in P(i) with muscle disuse has a significant effect on the cytosolic phosphorylation potential during transient ischemia and increases the intracellular buffering capacity of skeletal muscle.

Topics: Adenosine Triphosphate; Animals; Female; Hindlimb; Hindlimb Suspension; Ischemia; Magnetic Resonance Spectroscopy; Mice; Mice, Inbred Strains; Mitochondria, Muscle; Muscle Weakness; Muscle, Skeletal; Muscular Atrophy; Phosphates; Phosphocreatine; Phosphorylation; Protons; Rest

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

In experiments on rats we studied the effects of cardioplegic solutions with L-aspartic acid or L-arginine on functional recovery and metabolism of isolated working heart after 40-min normothermal global ischemia and 30-min reperfusion. After reperfusion of the hearts preventively protected with cardioplegic solution containing L-aspartic acid or L-arginine, coronary flow decreased in comparison with the initial values. As a component of cardioplegic solution, L-arginine was less efficient in recovery of contractility and cardiac output of the hearts in comparison with L-aspartic acid. In hearts protected with L-aspartic acid, the postischemic levels of ATP and phosphocreatine were significantly higher, and the level of lactate was significantly lower than in hearts protected with L-arginine. In comparison with L-arginine, L-aspartic acid is a more efficient component of cardioplegic solution in protection of the heart from metabolic and functional damages caused by global ischemia and reperfusion.

Topics: Adenosine Triphosphate; Animals; Arginine; Aspartic Acid; Blood Pressure; Cardioplegic Solutions; Catalysis; Ischemia; Lactates; Phosphocreatine; Rats; Rats, Wistar; Reperfusion Injury; Time Factors

Antinecrotic activity of 2-ethyl-6-methyl-3 oxipyridin succinate (mexidol) and pentoxifylline (trental) was investigated on 32 mail rats with average body-weight of 170-220 g. Under the influence of mexidol and trental, which were injected 15 min before the insection of skin graft and then once per day during 3 days, necrotized area of skin graft is reduced by 22 and 15%, the amount of lost keranocytes--by 33 and 30%. In skin graft homogenates under the influence of mexidol rises the reduced under ischemia succinate dehydrogenase activity, while under trental influence it does not change. Under the influence of mexidol and trental on third day content of ATP rises by 29,5 and 19,5 %, ADP increases and decreases by 27%, creatinphosphate--by 33 and 21% correspondingly. Trentale improves elasticity of erythrocytes. It is suggested, that positive effect of mexidol on skin graft is conditioned by its ability to activate succinate-dependent detour in oxygen phosphorilation chain of mitochondries and to raise content of ubiquinone, whereas the effect of trental relates with intensification of microcirculation, delivery of oxygen on periphery. That allows recommending combined use of preparations in ischemia of skin.

Topics: Adenosine Diphosphate; Adenosine Triphosphate; Animals; Electron Transport Complex II; Graft Survival; Ischemia; Keratinocytes; Male; Necrosis; Pentoxifylline; Phosphocreatine; Picolines; Rats; Skin; Skin Transplantation; Surgical Flaps

Reamberin in a dose of 25 mg/kg (succinate concentration) was injected intravenously for 3 days starting from the 1st hour after skin ischemia modeling. This treatment decreased activities of lactate dehydrogenase, aspartate transaminase, and creatine phosphokinase in skin homogenates by 1.6 times, 19%, and 51.3%, respectively. The index of cytolysis decreased by 18%. Reamberin had an energotropic effect, which manifested in an increase in the total ATP content and concentration of creatine phosphate (by 16 and 10%, respectively). After administration of Reamberin, activity of the succinate-ubiquinone reductase system increased by 17%. Under these conditions succinate dehydrogenase activity exceeded the normal by 21%. Reamberin had no effect on the mitochondrial NADH-ubiquinone reductase system in dermal cells during skin ischemia. Superoxide dismutase activity in the area of necrosis increased to the control level on day 3 of treatment with Reamberin. Activities of catalase and glutathione peroxidase increased by 13 and 19%, respectively. Our results indicate that the course of intravenous treatment with Reamberin for 3 days contributes to an increase in reserve capacities of the antioxidant protection system and produces a protective effect during skin ischemia.

Topics: Adenosine Triphosphate; Animals; Antioxidants; Aspartate Aminotransferases; Creatine Kinase; Electron Transport Complex II; Ischemia; L-Lactate Dehydrogenase; Male; Mitochondria; Phosphocreatine; Rats; Rats, Inbred Strains; Skin; Succinates; Superoxide Dismutase

Multiple organ failure subsequent to intestinal ischaemia and reperfusion (I/R) includes cardiac failure, but little is known about heart energy metabolism in this setting. This study investigates the effects of intestinal I/R on heart energy metabolism and evaluates the effects of moderate hypothermia.. Adult rats underwent intestinal ischaemia for 60 minutes followed by 120 minutes of reperfusion. Animals were maintained at either normothermia (36 degrees to 38 degrees C) or moderate hypothermia (30 degrees to 32 degrees C). In experiment A, 2 groups were studied: (1) sham at normothermia; (2) I/R at normothermia. After death, the heart was removed. Cardiac phosphoenergetics were assessed by 31P magnetic resonance spectroscopy; data are expressed as micromoles per gram. In experiment B, 4 groups were studied: (1) sham at normothermia, (2) I/R at normothermia, (3) sham at hypothermia, (4) I/R at hypothermia. At the end of the experiment, the heart was harvested. The activity of carnitine palmitoyl transferase I (CPT I), an important enzyme in the control of fatty acid oxidation, was measured; data are expressed as nanomoles per minute per unit citrate synthase. Results are expressed as mean +/- SEM.. In experiment A, there were no differences between the 2 study groups in cardiac phosphocreatine, inorganic phosphate, adenosine triphosphate (ATP), or in the ratio of inorganic phosphate to ATP. In experiment B, CPT I activity was decreased significantly after I/R at normothermia compared with normothermic sham, but this enzyme inhibition was prevented by hypothermia (3.9 +/- 0.2; v I/R).. These results suggest that although cardiac ATP supply was maintained during intestinal I/R at normothermia, the balance of substrate utilisation was shifted from fatty acid oxidation to carbohydrate utilisation. However, moderate hypothermia modified these changes. The beneficial effect of moderate hypothermia on cardiac metabolism during intestinal I/R has potential clinical application in various surgical conditions.

Topics: Adenosine Triphosphate; Animals; Carnitine O-Palmitoyltransferase; Energy Metabolism; Hypothermia, Induced; Intestines; Ischemia; Magnetic Resonance Spectroscopy; Male; Myocardium; Phosphates; Phosphocreatine; Rats; Rats, Sprague-Dawley; Reperfusion; Reperfusion Injury

We sought to know whether a free radical spin trap agent, alpha-phenyl-N-tert-butyl nitrone (PBN) influences brain cell membrane function and energy metabolism during and after transient global hypoxia-ischemia (HI) in the newborn piglets. Cerebral HI was induced by temporary complete occlusion of bilateral common carotid arteries and simultaneous breathing with 8% oxygen for 30 min, followed by release of carotid occlusion and normoxic ventilation for 1 hr (reoxygenation-reperfusion,RR). PBN (100 mg/kg) or vehicle was administered intravenously just before the induction of HI or RR. Brain cortex was harvested for the biochemical analyses at the end of HI or RR. The level of conjugated dienes significantly increased and the activity of Na+, K+ -ATPase significantly decreased during HI,and they did not recover during RR. The levels of ATP and phosphocreatine (PCr)significantly decreased during HI, and recovered during RR. PBN significantly decreased the level of conjugated dienes both during HI and RR, but did not influence the activity of Na+, K+ -ATPase and the levels of ATP and PCr. We demonstrated that PBN effectively reduced brain cell membrane lipid peroxidation, but did not reverse ongoing brain cell membrane dysfunction nor did restore brain cellular energy depletion, in our piglet model of global hypoxic-ischemic brain injury.

Topics: Adenosine Triphosphate; Animals; Animals, Newborn; Brain; Cell Membrane; Cerebral Cortex; Cyclic N-Oxides; Hypoxia; Ischemia; Lipid Peroxidation; Neuroprotective Agents; Nitrogen Oxides; Phosphocreatine; Reperfusion Injury; Sodium-Potassium-Exchanging ATPase; Swine; Time Factors

The effects of creatine (Cr) absence in skeletal muscle caused by a deletion of guanidinoacetate methyltransferase (GAMT) were studied in a knockout mouse model by in vivo (31)P magnetic resonance (MR) spectroscopy. (31)P MR spectra of hindleg muscle of GAMT-deficient (GAMT-/-) mice showed no phosphocreatine (PCr) signal and instead showed the signal for phosphorylated guanidinoacetate (PGua), the immediate precursor of Cr, which is not normally present. Tissue pH did not differ between wild-type (WT) and GAMT-/- mice, while relative inorganic phosphate (P(i)) levels were increased in the latter. During ischaemia, PGua was metabolically active in GAMT-/- mice and decreased at a rate comparable to the decrease of PCr in WT mice. However, the recovery rate of PGua in GAMT-/- mice after ischaemia was reduced compared to PCr in WT mice. Saturation transfer measurements revealed no detectable flux from PGua to gamma-ATP, indicating severely reduced enzyme kinetics. Supplementation of Cr resulted in a rapid increase in PCr signal intensity until only this resonance was visible, along with a reduction in relative P(i) values. However, the PGua recovery rate after ischaemia did not change. Our results show that despite the absence of Cr, GAMT-/- mice can cope with mild ischaemic stress by using PGua for high energy phosphoryl transfer. The reduced affinity of creatine kinase (CK) for (P)Gua only becomes apparent during recovery from ischaemia. It is argued that absence of Cr causes the higher relative P(i) concentration also observed in animals lacking muscle CK, indicating an important role of the CK system in P(i) homeostasis.

Topics: Adenosine Triphosphate; Animals; Creatine; Glycine; Guanidinoacetate N-Methyltransferase; Homeostasis; Ischemia; Methyltransferases; Mice; Mice, Knockout; Muscle, Skeletal; Phenotype; Phosphocreatine; Phosphorylation; Rest

In skeletal muscle, intracellular Po2 can fall to as low as 2-3 mmHg. This study tested whether oxygen regulates cellular respiration in this range of oxygen tensions through direct coupling between phosphorylation potential and intracellular Po2. Oxygen may also behave as a simple substrate in cellular respiration that is near saturating levels over most of the physiological range. A novel optical spectroscopic method was used to measure tissue oxygen consumption (Mo2) and intracellular Po2 using the decline in hemoglobin and myoglobin saturation in the ischemic hindlimb muscle of Swiss-Webster mice. 31P magnetic resonance spectroscopic determinations yielded phosphocreatine concentration ([PCr]) and pH in the same muscle volume. Intracellular Po2 fell to <2 mmHg during the ischemic period without a change in the muscle [PCr] or pH. The constant phosphorylation state despite the decline in intracellular Po2 rejects the hypothesis that direct coupling between these two variables results in a regulatory role for oxygen in cellular respiration. A second set of experiments tested the relationship between intracellular Po2 and Mo2. In vivo Mo2 in mouse skeletal muscle was increased by systemic treatment with 2 and 4 mg/kg body wt 2,4-dinitrophenol to partially uncouple mitochondria. Mo2 was not dependent on intracellular Po2 above 3 mmHg in the three groups despite a threefold increase in Mo2. These results indicate that Mo2 and the phosphorylation state of the cell are independent of intracellular Po2 throughout the physiological range of oxygen tensions. Therefore, we reject a regulatory role for oxygen in cellular respiration and conclude that oxygen acts as a simple substrate for respiration under physiological conditions.

Topics: 2,4-Dinitrophenol; Animals; Cell Respiration; Female; Hydrogen-Ion Concentration; Ischemia; Magnetic Resonance Spectroscopy; Mice; Mitochondria; Muscle, Skeletal; Oxygen; Oxygen Consumption; Phosphocreatine; Phosphorus Isotopes; Phosphorylation; Uncoupling Agents

Substantial ATP supply by glycolysis is thought to reflect cellular anoxia in vertebrate muscle. An alternative hypothesis is that the lactate generated during contraction reflects sustained glycolytic ATP supply under well-oxygenated conditions. We distinguished these hypotheses by comparing intracellular glycolysis during anoxia to lactate efflux from muscle during sustained, aerobic contractions. We examined the tailshaker muscle of the rattlesnake because of its uniform cell properties, exclusive blood circulation, and ability to sustain rattling for prolonged periods. Here we show that glycolysis is independent of the O(2) level and supplies one-third of the high ATP demands of sustained tailshaking. Fatigue is avoided by rapid H(+) and lactate efflux resulting from blood flow rates that are among the highest reported for vertebrate muscle. These results reject the hypothesis that glycolysis necessarily reflects cellular anoxia. Instead, they demonstrate that glycolysis can provide a high and sustainable supply of ATP along with oxidative phosphorylation without muscle fatigue.

Topics: Adenosine Triphosphate; Aerobiosis; Animal Communication; Animals; Blood Pressure; Body Temperature; Citric Acid Cycle; Crotalus; Glycolysis; Hydrogen-Ion Concentration; Intracellular Fluid; Ischemia; Lactic Acid; Muscle Contraction; Muscle, Skeletal; Oxidative Phosphorylation; Oxygen Consumption; Phosphocreatine

In this study, we investigated the hypothesis that prolonged ischemia would impair both sarcoplasmic reticulum (SR) Ca(2+) uptake and Ca(2+) release in skeletal muscle. To induce total ischemia (I), a tourniquet was placed around the upper hindlimb in 30 female Sprague-Dawley rats [wt = 256 +/- 6.7 (SE) g] and inflated to 350 mmHg for 4 h. The contralateral limb served as control (C). Immediately after the 4 h of ischemia, mixed gastrocnemius and tibialis anterior muscle was sampled from both limbs, and both crude muscle homogenates and SR vesicles were prepared. In another 10 control animals (CC), muscles were sampled and prepared exactly the same way, but immediately after anesthetization. Ca(2+) uptake and Ca(2+) release were measured in vitro with Indo-I on both homogenates and SR vesicles. As hypothesized, submaximal Ca(2+) uptake was lower (P < 0.05) in I compared with CC and C, by 25 and 45% in homogenates and SR vesicles, respectively. Silver nitrate (AgNO(3))-induced Ca(2+) release, which occurred in two phases (phase 1 and phase 2), was also altered in I compared with CC and C, in both muscle homogenates and SR vesicles. With ischemia, phase 1 peak Ca(2+) release was 26% lower (P < 0.05) in SR vesicles only. For phase 2, peak Ca(2+) release was 54 and 24% lower (P < 0.05) in SR vesicles and homogenates, respectively. These results demonstrate that prolonged skeletal muscle ischemia leads to a reduced SR Ca(2+) uptake in both homogenates and SR vesicles. The effects of ischemia on SR Ca(2+) release, however, depend on both the phase examined and the type of tissue preparation.

Topics: Adenosine Triphosphate; Animals; Calcium; Creatine; Enzyme Inhibitors; Female; Fluorescent Dyes; Glycogen; Hindlimb; Indoles; Ischemia; Lactic Acid; Muscle Contraction; Muscle, Skeletal; Oxalic Acid; Phosphates; Phosphocreatine; Rats; Rats, Sprague-Dawley; Ryanodine; Sarcoplasmic Reticulum; Silver Nitrate

Distribution of total creatine (free creatine + phosphocreatine) between two subcellular macrocompartments--mitochondrial matrix space and cytoplasm--in heart and skeletal muscle cells was reinvestigated by using a permeabilized cell technique. Isolated cardiomyocytes were treated with saponin (50 microg/ml for 30 min or 600 microg/ml for 1 min) to open the outer cellular membrane and release the metabolites from cytoplasm (cytoplasmic fraction, CF). All mitochondrial population in permeabilized cells remained intact: the outer membrane was impermeable for exogenous cytochrome c, the acceptor control index of respiration exceeded 10, the mitochondrial creatine kinase reaction was fully coupled to the adenine nucleotide translocator. Metabolites were released from mitochondrial fraction (MF) by 2-5% Triton X100. Total cellular pool of free creatine + phosphocreatine (69.6 +/- 2.1 nmoles per mg of protein) was found exclusively in CF and was practically absent in MF. When fibers were prepared from perfused rat hearts, cellular distribution of creatine was not dependent on functional state of the heart and only slightly modified by ischemia. It is concluded that there is no stable pool of creatine or phosphocreatine in the mitochondrial matrix in the intact muscle cells, and the total creatine pool is localized in only one macrocompartment--cytoplasm.

Topics: Animals; Creatine; Cytoplasm; Ischemia; L-Lactate Dehydrogenase; Male; Mitochondria; Muscle Fibers, Skeletal; Muscle, Skeletal; Myocardium; Perfusion; Phosphocreatine; Rats; Rats, Wistar; Reperfusion; Time Factors

To investigate the hypothesis that ischemia and reperfusion would impair sarcoplasmic reticulum (SR) Ca(2+) regulation in skeletal muscle, Sprague-Dawley rats (n = 20) weighing 290 +/- 3.5 g were randomly assigned to either a control control (CC) group, in which only the effects of anesthetization were studied, or to a group in which the muscles in one hindlimb were made ischemic for 4 h and allowed to recover for 1 h (I). The nonischemic, contralateral muscles served as control (C). Measurements of Ca(2+)-ATPase properties in homogenates and SR vesicles, in mixed gastrocnemius and tibialis anterior muscles, indicated no differences between groups on maximal activity, the Hill coefficient, and Ca(50), defined as the Ca(2+) concentration needed to elicit 50% of maximal activity. In homogenates, Ca(2+) uptake was lower (P < 0.05) by 20-25%, measured at 0.5 and 1.0 microM of free Ca(2+) ([Ca(2+)](f)) in C compared with CC. In SR vesicles, Ca(2+) uptake was lower (P < 0.05) by 30-38% in I compared with CC at [Ca(2+)](f) between 0.5 and 1.5 microM. Silver nitrate induced Ca(2+) release, assessed during both the initial, early rapid (phase 1), and slower, prolonged late (phase 2) phases, in homogenates and SR vesicles, indicated a higher (P < 0.05) release only in phase 1 in SR vesicles in I compared with CC. These results indicate that the alterations in SR Ca(2+) regulation, previously observed after prolonged ischemia by our group, are reversed within 1 h of reperfusion. However, the lower Ca(2+) uptake observed in long-term, nonischemic homogenates suggests that altered regulation may occur in the absence of ischemia.

Topics: Animals; Biological Transport; Calcium; Calcium-Transporting ATPases; Creatine; Female; Glycogen; Hindlimb; Ischemia; Kinetics; Lactates; Muscle Contraction; Muscle, Skeletal; Phosphates; Phosphocreatine; Rats; Rats, Sprague-Dawley; Reference Values; Reperfusion; Sarcoplasmic Reticulum; Time Factors

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

To investigate the hypothesis that prolonged partial ischemia would result in a depression in homogenate sarcoplasmic reticulum (SR) Ca2+-sequestering and mechanical properties in muscle, a cuff was placed around the hindlimb of 8 adult Sprague-Dawley rats (267+/-5.8 g; x +/- S.E.) and partially inflated (315 mm Hg) for 2 h. Following occlusion, the EDL was sampled both from the ischemic (I) and contralateral control (C) leg and SR properties compared with the EDL muscles extracted from rats (n = 8) immediately following anaesthetization (CC). Ischemia was indicated by a lower (p < 0.05) concentration (mmol.kg dry wt(-1)) of ATP (19.0+/-0.7 vs. 16.7+/-0.7) and phosphocreatine (58.1+/-5.7 vs. 35.0+/-4.6) in I compared to C. Although Ca2+-ATPase activity (micromol x g protein(-1) x sec(-1)), both maximal and submaximal, was not different between C and I (19.7+/-0.4 vs. 18.5+/-1.3), reductions (p < 0.05) in Ca2+-uptake (mmol x g protein(-1) x sec(-1)) of between 18.2 and 24.7% across a range of submaximal free Ca2+-levels were observed in I compared to C. Lower submaximal Ca2+-ATPase activity and Ca2+-uptake were also observed in the EDL in C compared to CC animals. Time dependent reductions (p < 0.05) were found in peak twitch and maximal tetanic tension in EDL from I but not C. It is concluded that partial ischemia, resulting in modest reductions in energy state in EDL, induces a reduction in Ca2+-uptake independent of changes in Ca2+-ATPase activity. These changes reduce the coupling ratio and the efficiency of Ca2+-transport by SR.

Topics: Animals; Calcimycin; Calcium; Calcium-Transporting ATPases; Energy Metabolism; Hindlimb; In Vitro Techniques; Ion Transport; Ischemia; Lactic Acid; Male; Muscle Contraction; Phosphocreatine; Rats; Rats, Sprague-Dawley; Ryanodine; Sarcoplasmic Reticulum; Time Factors

Ruptured abdominal aortic aneurysm (RAAA) repair, a combination of hemorrhagic shock and lower-torso ischemia, is associated with a 50-70% mortality. Myocardial dysfunction may contribute to the high rate of mortality after aneurysm repair. We attempted to determine whether RAAA repair results in cardiac dysfunction mediated by tumor necrosis factor-alpha (TNF-alpha). We modeled aortic rupture and repair in the rat by inducing hemorrhagic shock to a mean blood pressure of 50 mmHg for 1 h, followed by supramesenteric clamping of the aorta for 45 min. After 90 min of reperfusion, cardiac contractile function was assessed with a Langendorff preparation. Myocardial TNF-alpha, ATP and creatine phosphate (CP) levels, and markers of oxidant stress (F(2)-isoprostanes) were measured. Cardiac function in the combined shock and clamp rats was significantly depressed compared with sham-operated control rats but was similar to that noted in animals subjected to shock alone. Myocardial TNF-alpha concentrations increased 10-fold in the combined shock and clamp rats compared with sham rats, although there was no difference in myocardial ATP, CP, or F(2)-isoprostanes. TNF-alpha neutralization improved cardiac function by 50% in the combined shock and clamp rats. Hemorrhagic shock is the primary insult inducing cardiac dysfunction in this model of RAAA repair. An improvement in cardiac contractile function after immunoneutralization of TNF-alpha indicates that TNF-alpha mediates a significant portion of the myocardial dysfunction in this model.

Topics: Adenosine Triphosphate; Aneurysm, Ruptured; Animals; Antibodies; Aorta; Aortic Aneurysm, Abdominal; Cardiomyopathies; Constriction; Ischemia; Male; Myocardium; Peroxidase; Phosphocreatine; Rats; Rats, Sprague-Dawley; Shock, Hemorrhagic; Tumor Necrosis Factor-alpha; Ventricular Function, Left

Ischemia and reperfusion were studied in isolated working rat hearts and in exarticulated rat hind limbs. Free radicals are known to be generated in ischemia/reperfusion and to propagate complications. To reduce reperfusion injury, 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 reperfusion. 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). This compound accelerates and stabilizes the recovery of the aortic flow. With dihydrolipoate, ATP synthesis is increased, ATPase activity (ATP hydrolysis) reduced, intracellular creatine kinase activity maintained and thus phosphocreatine contents are higher than in controls. For exarticulated rat hind limbs, the dihydrolipoate group contained 8.3 microM in the modified reperfusate. 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 from cells was significantly lower with dihydrolipoate. Lipoate/dihydrolipoate effectively reduced reperfusion injury in isolated working rat hearts and in exarticulated rat hind limbs after extended ischemia. Finally, the compound was successfully applied in an in vivo pig hind limb model.

Topics: Adenosine Triphosphate; Animals; Antioxidants; Aorta, Thoracic; Cell Hypoxia; Constriction; Creatine Kinase; Drug Evaluation, Preclinical; Free Radical Scavengers; Hindlimb; Iliac Artery; Ischemia; Isoenzymes; Magnetic Resonance Spectroscopy; Male; Mitochondria, Heart; Muscle Contraction; Muscle Proteins; Myocardial Ischemia; Myocardial Reperfusion Injury; Oxidative Stress; Phosphocreatine; Rats; Rats, Wistar; Reperfusion Injury; Swine; Thioctic Acid

This study examined the changes in myocardial energy metabolism during myocardial ischemia after "remote preconditioning" and investigated the involvement of adenosine receptors in the mechanisms of this effect.. Recent studies have indicated that a brief period of ischemia and reperfusion (ischemic preconditioning, PC) in a remote organ reduces myocardial infarct size (IS) protecting against subsequent sustained myocardial ischemia. However, the mechanisms of "remote PC" remain unclear. We assessed myocardial energy metabolism during sustained myocardial ischemia and reperfusion after renal PC (RPC), in comparison with that after myocardial PC (MPC) in open-chest rabbits. It has been established that adenosine receptors are involved in the mechanisms of MPC.. Rabbits that had been anesthetized with halothane were divided into six groups. The control (CNT) group underwent 40-min coronary occlusion followed by 120 min reperfusion. Before the procedure, the MPC group underwent an additional protocol of 5 min coronary artery occlusion and 20 min reperfusion, and the RPC group received a 10 min episode of renal artery occlusion and 20 min reperfusion. In additional experimental groups, 8 sulfophenyl-theophylline (SPT, 10 mg/kg), an adenosine receptor inhibitor, was intravenously injected before the 40 min myocardial ischemia (SPT, MPC + SPT and RPC + SPT groups, respectively). Myocardial levels of phosphocreatine (PCr), ATP and intracellular pH (pHi) were measured by 31P-NMR spectroscopy.. RPC and MPC delayed the decreases in ATP levels, preserved pHi during 40-min myocardial ischemia and resulted in better recovery of ATP and PCr during 120 min reperfusion compared with the controls. SPT abolished the improvement in myocardial energy metabolism and the reduction in myocardial IS caused by MPC or RPC. Myocardial IS in the CNT (n = 8), MPC (n = 9), RPC (n = 9), SPT (n = 6), MPC + SPT (n = 8) and RPC + SPT (n = 8) groups averaged 42.8+/-3.5%, 18.2+/-1.8%*, 19.6+/-1.3%*, 44.9+/-5.0%, 35.6+/-2.7% and 34.8+/-3.6% of the area at risk (*p < 0.05 vs. CNT), respectively.. PC in a remote organ, similar to MPC, improved myocardial energy metabolism during ischemia and reperfusion and reduced IS in vivo by an adenosine-dependent mechanism in rabbits.

Topics: Adenosine Triphosphate; Animals; Energy Metabolism; Hydrogen-Ion Concentration; Infusions, Intravenous; Intracellular Fluid; Ischemia; Ischemic Preconditioning, Myocardial; Kidney; Magnetic Resonance Spectroscopy; Male; Myocardial Ischemia; Myocardium; Phosphocreatine; Pilot Projects; Purinergic P1 Receptor Antagonists; Rabbits; Receptors, Purinergic P1; Theophylline

Muscle-type phosphofructokinase (M-PFK) deficiency causes an exertional myopathy and chronic hemolysis in affected humans and dogs, the only animal model available. Deficient individuals have impaired glycolytic metabolism, impaired oxidative metabolism, and increased hemoglobin-oxygen (HbO2) affinity as a result of low 2,3-diphosphoglycerate (2,3-DPG) levels. The purpose of this study was to determine if PFK-deficient muscle has abnormal oxygen saturation during exercise. Oxygen saturation of hemoglobin/myoglobin was measured noninvasively in skeletal muscle during progressive muscle activation using near-infrared spectroscopy (NIRS). Muscle metabolites were also measured using magnetic resonance spectroscopy (MRS). PFK-deficient and normal dogs were anesthetized and the cranial tibial muscles stimulated for 6 min at each of four different rates (1, 2, 4, and 8 Hz). With increasing stimulation, muscles from normal dogs showed progressive decrease in hemoglobin saturation. In contrast, PFK-deficient dogs exhibited either an increase in hemoglobin saturation or an initial decrease with no further change. PFK-deficient muscles accumulated 11.1 +/- 3.5 mmol/L of sugar phosphate which was not seen in normal muscle and had higher calculated [ADP] levels at each stimulation level, indicating impaired oxidative metabolism. These findings are consistent with the hypothesis that these animals have impaired oxidative metabolism and impaired muscle O2 extraction from hemoglobin due to increased HbO2 affinity. NIRS appears to be a useful noninvasive method of monitoring tissue oxygen saturation in normal or disease conditions.

Topics: Adenosine Diphosphate; Adenosine Triphosphate; Animals; Creatine Kinase; Dogs; Electric Stimulation; Erythrocytes; Glycogen Storage Disease Type VII; Hydrogen-Ion Concentration; Ischemia; Magnetic Resonance Imaging; Muscle, Skeletal; Oxyhemoglobins; Phosphocreatine; Phosphorus Isotopes; Physical Exertion; Spectroscopy, Near-Infrared; Sugar Phosphates

Energy metabolism and interstitial fluid displacement were studied in the human gastrocnemius during three subsequent 5-min ischemia-reperfusion periods [ischemic preconditioning (IP)]. The muscle energy balance was assessed by combining near-infrared spectroscopy (NIRS) and 31P-nuclear magnetic resonance spectroscopy (31P-NMRS). The interstitial fluid displacement was determined by combining NIRS and 23Na-NMRS. No changes in total energy consumption or in the fractional contribution of the underlying energy sources (aerobic glycolysis, anaerobic glycolysis, and Lohmann reaction) were observed in the muscle during the tested IP protocol. Oxygen consumption in the muscle region of interest, as estimated by NIRS, was approximately 8 micromol . 100 g-1 . min-1 and did not change during IP. Phosphocreatine and ATP concentrations did not change over the whole experimental period. A slight but significant (P < 0.05) increase in intracellular pH was observed. Compared with the control, a 10% greater interstitial fluid content per muscle unit volume was observed at the end of the IP protocol. It is concluded that, at variance with cardiac muscle, repeated 5-min ischemia-reperfusion cycles do not induce metabolic changes in human gastrocnemius but alter the interstitial fluid readjustment. The techniques developed in the present study may be useful in identifying protocols suitable for skeletal muscle preconditioning and to explain the functional basis of this procedure.

Topics: Adenosine Triphosphate; Aerobiosis; Energy Metabolism; Extracellular Space; Female; Hemoglobins; Humans; Ischemia; Kinetics; Magnetic Resonance Spectroscopy; Male; Models, Biological; Muscle, Skeletal; Oxygen; Oxygen Consumption; Oxyhemoglobins; Phosphocreatine; Spectrophotometry, Infrared; Time Factors

We measured significant undershoots of the concentrations of free ADP ([ADP]) and Pi ([Pi]) and the free energy of ATP hydrolysis (DeltaGATP) below initial resting levels during recovery from severe ischemic exercise with 31P-nuclear magnetic resonance spectroscopy in 11 healthy sports students. Undershoots of the rate of oxidative phosphorylation would be predicted if the rate of oxidative phosphorylation would depend solely on free [ADP], [Pi], or DeltaGATP. However, undershoots of the rate of oxidative phosphorylation have not been reported in the literature. Furthermore, undershoots of the rate of oxidative phosphorylation are unlikely because there is evidence that a balance between ATP production and consumption cannot be achieved if an undershoot of the rate of oxidative phosphorylation actually occurs. Therefore, oxidative phosphorylation seems to depend not only on free [ADP], [Pi], or DeltaGATP. An explanation is that acidosis-related or other factors control oxidative phosphorylation additionally, at least under some conditions.

Topics: Adenosine Diphosphate; Adenosine Triphosphate; Adult; Energy Metabolism; Exercise; Female; Humans; Hydrogen-Ion Concentration; Hydrolysis; Ischemia; Isometric Contraction; Magnetic Resonance Spectroscopy; Male; Muscle, Skeletal; Oxidative Phosphorylation; Phosphates; Phosphocreatine; Thermodynamics

The ability of skeletal muscle to recover high energy phosphate compounds in response to pretreatment with vitamin E was investigated in a rabbit hindlimb ischemia/reperfusion model (2. 5 h/2 h). High energy metabolites were measured in the adductor magnus muscle of untreated animals and compared to the treatment group (all rac-alpha-tocopheryl acetate, 3 mg/kg body weight, supplemented i.v. before the onset of ischemia). Phosphocreatine (PCr) levels decreased after ischemia more than 65% in untreated and treatment groups, but tended to recover in treatment group after reperfusion. Adenosine triphosphate (ATP) values decreased by 50% of basal level after reperfusion in the untreated group, whereas alpha-tocopherol pretreatment prevented ATP depletion.

Topics: Adenosine Triphosphate; alpha-Tocopherol; Animals; Energy Metabolism; Hindlimb; Ischemia; Male; Muscle, Skeletal; Phosphocreatine; Rabbits; Reperfusion; Tocopherols; Vitamin E

Allopurinol (AP) protects skeletal muscle function against ischaemia-induced injury, but the mechanism is not yet clear. As AP acts as a competitive xanthine oxidase inhibitor, both a reduction of oxygen-derived free radicals and an enhancement of purine resynthesis (salvage pathway) might be involved. We investigated the in vivo kinetics of high-energy phosphates in skeletal muscle after AP pretreatment using 31P-magnetic resonance spectroscopy during 2 h of ischaemia and 3 h of reperfusion in rat hindlimbs. Three animals (group A) were pretreated with a total of 160 mg/kg AP i.p., 3 control animals (group B) received the same amount of 0.9% saline solution. ATP decreased to 18.6 +/- 1.3% of the pre-ischaemic value in group A and to 17.3 +/- 2.8% in group B after 2 h of ischaemia, and rose to only 47.7 +/- 1.5 and 50.5 +/- 1.8%, respectively, after 3 h of reperfusion. Phosphocreatine fell to 7.2 +/- 2.9 and 7.6 +/- 2.2% of pre-ischaemic values after 2 h of ischaemia and rose again to 36.5 +/- 12.9 and 45.4 +/- 20.4% after 3 h of reperfusion. Inorganic phosphate (Pi) increased 5-fold after 2 h of ischaemia, irrespective of the treatment. After 3 h of reperfusion, Pi was still 4 times the pre-ischaemic value. The kinetics of ATP, PCr, and Pi levels were not statistically different between the two groups. These results indicate that the ATP salvage pathway does not play an important role in AP-induced attenuation of ischaemia/reperfusion-induced muscle damage.

Topics: Adenosine Triphosphate; Allopurinol; Animals; Ischemia; Magnetic Resonance Spectroscopy; Male; Muscle, Skeletal; Phosphocreatine; Rats; Rats, Wistar; Reperfusion Injury

Skeletal muscle contraction during ischemia, such as that experienced by peripheral vascular disease patients, is characterized by rapid fatigue. Using a canine gracilis model, we tested the hypothesis that a critical factor determining force production during ischemia is the metabolic response during the transition from rest to steady state. Dichloroacetate (DCA) administration before gracilis muscle contraction increased pyruvate dehydrogenase complex activation and resulted in acetylation of 80% of the free carnitine pool to acetylcarnitine. After 1 min of contraction, phosphocreatine (PCr) degradation in the DCA group was approximately 50% lower than in the control group (P < 0.05) during conditions of identical force production. After 6 min of contraction, steady-state force production was approximately 30% higher in the DCA group (P < 0.05), and muscle ATP, PCr, and glycogen degradation and lactate accumulation were lower (P < 0.05 in all cases). It appears, therefore, that an important determinant of contractile function during ischemia is the mechanisms by which ATP regeneration occurs during the period of rest to steady-state transition.

Topics: Acetylcarnitine; Animals; Dichloroacetic Acid; Dogs; Homeostasis; In Vitro Techniques; Ischemia; Muscle Contraction; Muscle, Skeletal; NAD; Phosphocreatine; Regional Blood Flow; Rest; Time Factors

Relationships between pH and the concentrations of phosphocreatine (PCr), inorganic phosphate (Pi), and lactate during ischemic exercise depend on passive buffering, proton consumption as a consequence of net PCr breakdown, the control of glycogenolysis, (particularly in relation to the concentration of Pi, a substrate of glycogen phosphorylase that is produced by net PCr breakdown), and the creatine kinase equilibrium. The author analyzes the implications of these relationships for the interpretation of 31P-magnetic resonance spectroscopic data and for the control of glycogenolysis. For realistic adenosine diphosphate (ADP) concentrations, given the constraints of the creatine kinase equilibrium, the pH must be near-linear with lactate, with an apparent buffer capacity (i.e., the ratio of lactate accumulation to pH change) that is nearly twice the true buffer capacity (i.e., the ratio of net proton loading to pH change). The implications for glycogenolytic control depend on adenosine triphosphate (ATP) turnover, but an upper limit of activation of glycogen phosphorylase (i.e., the amount of the a form) that would permit no increase in ADP concentration can be calculated. Phosphorylase activation during ischemic exercise seems approximately proportional to the power output, consistent with calcium stimulation of phosphorylase b kinase. In simulations, ADP concentration is highly sensitive to this proportionality, as (unlike in purely oxidative exercise) ADP concentration is not known to participate in any closed feedback loops in ischemic exercise.

Topics: Adenosine Diphosphate; Adenosine Triphosphate; Buffers; Computer Simulation; Exercise; Glycogen; Humans; Hydrogen-Ion Concentration; Ischemia; Lactates; Magnetic Resonance Spectroscopy; Muscles; Phosphates; Phosphocreatine; Phosphorus

Topics: Adenine Nucleotides; Adenosine; Adenosine Triphosphate; Allopurinol; Animals; Energy Metabolism; Glutathione; Hypoxanthine; Insulin; Ischemia; Jejunum; Mesenteric Artery, Superior; Organ Preservation; Organ Preservation Solutions; Oxygen; Phosphocreatine; Portal Vein; Raffinose; Rats; Rats, Wistar; Reperfusion; Reperfusion Injury

Topics: Adenosine Triphosphate; Hemoglobins; Humans; Hydrogen-Ion Concentration; Ischemia; Ischemic Preconditioning; Leg; Magnesium; Magnetic Resonance Spectroscopy; Muscle, Skeletal; Oxyhemoglobins; Phosphocreatine; Phosphorus; Reperfusion; Sodium; Spectrophotometry, Infrared; Time Factors

The metabolic effects of partial ischemia on canine skeletal muscle were examined during 20 min of isometric contraction. A reduction in blood flow of approximately 75% resulted in an approximate 40% reduction in contractile function. Muscle lactate accumulation and phosphocreatine (PCr) hydrolysis were greater during ischemia, indicating a greater reliance on anaerobic ATP regeneration. Pyruvate dehydrogenase transformation to its active form (PDCa) during contraction was not affected by ischemia, such that PDCa did not appear to be a determinant of skeletal muscle fatigue. Acetylcarnitine concentration was greater during ischemic contraction and inversely correlated with PCr concentration (r = -0.79, P<0.01). Furthermore, acetylcarnitine accumulation and PCr degradation correlated with the degree of skeletal muscle fatigue (r = 0.56, P<0.05 and r = 0.70, P<0.01, respectively). Thus the greater the acetyl group oxidation, the lesser the contribution from anaerobic ATP provision and, subsequently, the smaller the degree of muscle fatigue observed. The metabolic characteristics of this model of ischemic muscle contraction are indistinguishable from the normal metabolic responses observed with increasing contractile intensity.

Topics: Acetylcarnitine; Adenosine Triphosphate; Animals; Dogs; Electric Stimulation; Energy Metabolism; Fatty Acids, Nonesterified; Female; Glycogen; Ischemia; Isometric Contraction; Kinetics; Lactates; Muscle Fatigue; Muscle, Skeletal; NAD; Phosphocreatine; Pyruvate Dehydrogenase Complex; Regional Blood Flow; Regression Analysis; Time Factors

Topics: Adenine Nucleotides; Adenosine; Allopurinol; Animals; Energy Metabolism; Glutathione; Heart; Heart Transplantation; Hemodynamics; Insulin; Ischemia; Myocardial Contraction; Organ Preservation; Organ Preservation Solutions; Phosphocreatine; Raffinose; Rats; Rats, Inbred Lew; Reperfusion; Time Factors; Transplantation, Heterotopic; Transplantation, Isogeneic

Prolonged tissue ischemia and subsequent reperfusion results in significant tissue injury due to the ischemic-reperfusion (IR) syndrome. Ischemic preconditioning (IPC) or adenosine (ADO) pretreatment are known to protect IR injury in cardiac muscle. Our aim was to determine whether IPC or ADO pretreatment attenuates and protects against ischemic tissue reperfusion injury in skeletal muscle. Rats were anesthetized and global hindlimb ischemia was induced by 60 min of suprarenal aortic clamping followed by 30 min of reperfusion period. The degree of skeletal muscle dysfunction was determined by decreases in maximum contractile force, and adenosine triphosphate (ATP) and creatine phosphate (CP) levels of extensor digitorum longus (EDL) muscle. The distal tendon of the EDL was attached to a force transducer for maximum isometric force measurement. Samples were taken from the EDL for measurement of ATP and CP levels. The following were protective protocols prior to the IR challenge: (1) four consecutive 5-min periods of ischemia separated by 5-min reperfusion periods (PC/I) or (2) i.v. adenosine infusion (350 microg/kg/min x 10 min, PC/A). Our data suggest that pretreatment with brief periods of ischemia or systemic ADO infusion attenuates ischemic tissue reperfusion injury in skeletal muscle. [Table: see text]

Topics: Adenosine Diphosphate; Adenosine Triphosphate; Analysis of Variance; Animals; Aorta, Abdominal; Hindlimb; Ischemia; Isometric Contraction; Male; Muscle, Skeletal; Phosphocreatine; Rats; Rats, Wistar; Reperfusion Injury; Time Factors

Changes in creatine compounds, especially the creatine phosphate to creatine ratio (CrP/Cr), are more sensitive indicators than changes in other metabolites for early ischemia in the different muscular tissues of heart, small intestine, skeletal muscle, and aorta. Changes in adenine nucleotide ratios are buffered by CrP reserves and the absolute concentration of adenine nucleotides can vary greatly between different muscular tissues. Accumulation of lactate is indicative of ischemia, but is not as sensitive as the ratio of CrP/Cr, but may better indicate the duration of ischemia. Glycerol also accumulates in muscular tissues during prolonged ischemia, so that consideration of both lactate and glycerol levels together, might confer a better estimate of the duration of ischemia of different muscular tissues.

Topics: Adenine Nucleotides; Animals; Chromatography, High Pressure Liquid; Energy Metabolism; Glycerol; Ischemia; Lactic Acid; Male; Muscle, Skeletal; Muscles; Oxygen; Phosphates; Phosphocreatine; Rats; Rats, Wistar; Temperature

The effects of 5-(N,N-dimethyl)amiloride, a potent and specific Na(+)-H+ exchange inhibitor, were investigated in isolated perfused rabbit hearts subjected to ischemia and reperfusion. Phosphorus 31-nuclear magnetic resonance spectroscopy was used to monitor intracellular pH, creatine phosphate, beta-adenosine triphosphate, and inorganic phosphate. After cardioplegic arrest with St. Thomas' Hospital solution, normothermic (37 degrees C) global ischemia was induced for 45 minutes, and the hearts were reperfused for 50 minutes. Dimethyl amiloride at 10 mumol/L, which has minimal inotropic and chronotropic effects on the nonischemic heart, was added to the cardioplegic solution. Treatment with dimethyl amiloride reduced the elevation of left ventricular end-diastolic pressure during and after the ischemia and improved the postischemic recovery of developed pressure from 76% +/- 3.2% at 30 minutes of reperfusion in control hearts (n = 6) up to 99% +/- 1.9% in hearts treated with dimethyl amiloride (n = 8). Dimethyl amiloride did not affect the decline in intracellular pH during ischemia for up to 30 minutes but enhanced the intracellular acidosis thereafter. The intracellular pH at the end of ischemia was 6.21 +/- 0.05 in control hearts compared with 5.24 +/- 0.17 in hearts treated with dimethyl amiloride (p < 0.05). During reperfusion, intracellular pH of hearts treated with dimethyl amiloride was less than control for 5 minutes, but subsequent recovery of intracellular pH was similar to control. Treatment with dimethyl amiloride did not affect creatine phosphate breakdown, inorganic phosphate accumulation, and beta-adenosine triphosphate depletion during 45 minutes of ischemia. The creatine phosphate resynthesis and inorganic phosphate reduction during reperfusion were also unaffected. These findings suggest that Na(+)-H+ exchange plays an important role not only during reperfusion but also during ischemia for the development of postischemic cardiac dysfunction most likely by inducing primary Na+ and secondary Ca2+ overload. Specific Na(+)-H+ exchange inhibitors like dimethyl amiloride would have a potential therapeutic profile in cardiac surgery, especially if added before ischemia.

Topics: Acidosis; Adenosine Triphosphate; Amiloride; Animals; Bicarbonates; Calcium; Calcium Chloride; Cardioplegic Solutions; Diastole; Energy Metabolism; Heart; Heart Arrest, Induced; Hydrogen-Ion Concentration; Ischemia; Magnesium; Magnetic Resonance Spectroscopy; Myocardial Contraction; Myocardial Reperfusion; Myocardial Reperfusion Injury; Myocardium; Phosphates; Phosphocreatine; Phosphorus Isotopes; Potassium Chloride; Rabbits; Sodium; Sodium Chloride; Sodium-Hydrogen Exchangers; Ventricular Function, Left; Ventricular Pressure

This investigation evaluated the effect of oxygenated perfluorochemical (PFC) perfusion on the viability of ischemic skeletal muscle compared to hypothermic preservation. Twenty-five hindlimbs of 13 white rabbits were divided into five groups: a PFC group (7 hr of ischemia with 6 hr of PFC perfusion), a PFC/ reperfusion group (8 hr of ischemia with 6 hr of PFC perfusion and 1 hr reperfusion), a hypothermia group (7 hr of ischemia with 6 hr of 4 degrees C cold preservation), a hypothermia/reperfusion group (8 hr of ischemia with 6 hr of 4 degrees C cold preservation and 1 hr of reperfusion), and a control group. The levels of adenine nucleotides, creatine phosphate, hypoxanthine, xanthine, and lipid peroxide were determined in each group. In the PFC and PFC/reperfusion groups, the ATP level remained at 90% of that in the control group. The hypoxanthine level in the hypothermia/reperfusion group was decreased to 70% of that in the hypothermia group and the xanthine level was increased to 130%. In the PFC and PFC/reperfusion groups, hypoxanthine and xanthine levels were much lower and were similar to those in the control group. Lipid peroxide levels were also lower in the PFC and PFC/reperfusion groups than in the hypothermia/reperfusion group. Electron microscopy showed that endothelial cells from the PFC/reperfusion groups were not swollen. These results suggest that PFC perfusion is superior to hypothermia in inhibiting the generation of free radicals and in preventing ischemia-reperfusion injury of skeletal muscle.

Topics: Adenine Nucleotides; Animals; Cryopreservation; Endothelium, Vascular; Energy Metabolism; Fluorocarbons; Hindlimb; Ischemia; Lipid Peroxides; Microscopy, Electron; Muscles; Perfusion; Phosphocreatine; Rabbits; Reactive Oxygen Species; Reperfusion Injury; Replantation; Xanthine; Xanthines

Newborn and 1-mo-old swine were exposed to identical durations (18 min) and degrees of hypoxia (O2 content = 4 mL/dL), to examine the effects of hypoxia on cerebral energy metabolism and intracellular pH (pHi) in vivo, using 31P and 1H nuclear magnetic resonance spectroscopy. Hypoxia produced the same extent of reductions in phosphocreatine (PCr) (63 +/- 28% and 65 +/- 10%, newborns and 1-mo-olds, respectively) and pHi (6.93 +/- 0.06 and 6.89 +/- 0.06, respectively) for either age group. The magnitude of changes in PCr, lactate, and pHi was larger for subgroups of data collected when cardiovascular instability was present, suggesting that hypotension and possibly reduced cerebral perfusion contributed to cerebral energy failure and lactic-acidosis for either age group. There were no correlations between the blood plasma glucose concentration at 18 min of hypoxia and the extent of change in PCr, lactate, or pHi for either age group. During a subsequent period of complete ischemia induced via cardiac arrest after 20 min hypoxia, the decline in PCr and nucleoside triphosphate (NTP), and increase in lactate followed similar rates compared with previously studied age-matched animals that were normoxic before ischemia. The rate constants for the change in PCr, NTP, and lactate followed similar rates compared with previously studied age-matched animals that were normoxic before ischemia. The rate constants for the change in PCr, NTP, and lactate during ischemia showed no correlation with the blood plasma glucose concentration measured immediately before cardiac arrest. These results suggest that cerebral glycolytic rates and energy utilization during ischemia are unaffected by a preceding interval of hypoxia and that hyperglycemia does not delay cerebral energy failure during hypoxia or combined hypoxic-ischemia.

Topics: Acidosis, Lactic; Animals; Animals, Newborn; Energy Metabolism; Glucose; Glycolysis; Hydrogen-Ion Concentration; Hypoxia; Ischemia; Phosphocreatine; Swine

A pressure cuff was applied to the legs of two human volunteers in order to stop any blood supply for a period of about 30 min. The affected muscle was monitored using proton magnetic resonance imaging (MRI), phosphorus magnetic resonance spectroscopy (MRS) and near infrared (NIR) spectroscopy before, during and after this procedure. The internal temperature of the tissue was also measured. The phase of water protons in muscle showed changes that were not accounted for by the measured temperature, but which correlated with the large increase in deoxyhaemoglobin and deoxymyoglobin observed with NIR as well as the decrease in PCr and increase in Pi observed with MRS. Little or no change was found in proton density or T2*. These results show that in vivo measurements of temperature using the chemical shift method may be confounded by changes in tissue oxygenation. They also show that T2* is an insensitive measure of changes in tissue oxygenation.

Topics: Constriction; Hemoglobins; Humans; Ischemia; Leg; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Male; Middle Aged; Muscle, Skeletal; Myoglobin; Phosphocreatine; Phosphorus; Reference Values; Spectrophotometry, Infrared; Temperature

Topics: Adenosine Triphosphate; Allopurinol; Animals; Energy Metabolism; Ischemia; Male; Muscle Fatigue; Muscle, Skeletal; Phosphocreatine; Rats; Rats, Wistar; Reference Values; Reperfusion Injury

The cytoprotective effect of prostaglandins (PG) was evaluated by in vivo 31P MR spectroscopy. Twenty rabbits were divided into two groups; the control group given physiological saline, and the PG group given prostaglandin E1 (0.5 microgram/kg/min). Each solution was infused for 8 min, after which complete hepatic ischemia was induced for 20 min, followed by reperfusion for 40 min. During ischemia, beta-ATP decreased to 23.6% and 42.3%, phosphomonoester increased to 260% and 200% of their initial values in the control and the PG groups, respectively. Inorganic phosphate also increased. After reperfusion, beta-ATP recovered to 65.2% and 96.5%, phosphomonoester to 130% and 110%, inorganic phosphate to 140% and 120% in the control and PG groups, respectively. The changes during ischemia were significantly smaller and the recoveries during reperfusion were more complete in the PG group. These results may confirm the cytoprotective effect of prostaglandins by in vivo 31P-MR spectroscopy.

Topics: Adenosine Triphosphate; Alprostadil; Animals; Ischemia; Liver; Magnetic Resonance Spectroscopy; Male; Phosphates; Phosphocreatine; Phosphorus; Rabbits

Little is known about the metabolic effects of ischaemia on high energy phosphates in vivo in smooth muscle. We have developed a method for reversibly occluding the uterine artery, which allows simultaneous measurement of uterine metabolites using 31P NMR spectroscopy, and intra-uterine pressure, in vivo during ischaemia. We have investigated the effects of repeated ischaemia on metabolites, intracellular pH and contractions in anaesthetized rats. Occlusion produced an immediate drop in uterine blood flow and decreased contractions. Although contractions recovered upon reperfusion after both occlusions, the contractile activity was less after the second period of occlusion, suggesting less resistance after a prior ischaemic period. Significant falls in [ATP] and [phosphocreatine] and an increase in [P(i)] occurred during both occlusions. These were all reversed within 30 min of reperfusion. There was a large drop in intracellular pH produced by occlusion, which was rapidly reversed upon reperfusion. The changes in metabolites and intracellular pH were similar during the repeated ischaemic period, to those occurring during the first ischaemic period suggesting no alteration in energy production or utilization had occurred, with prior exposure to ischaemia. The significance of these results to the functioning of the uterus in labour is briefly discussed.

Topics: Adenosine Triphosphate; Animals; Constriction; Female; Hydrogen-Ion Concentration; Intracellular Fluid; Ischemia; Magnetic Resonance Spectroscopy; Phosphates; Phosphocreatine; Phosphorus Isotopes; Postpartum Period; Rats; Rats, Wistar; Uterine Contraction; Uterus

Mitochondrial function in muscle in vivo can be quantitatively evaluated using 31-phosphorus nuclear magnetic resonance. In resting muscle, the concentrations of ions (e.g. H+, Na+) and two of the major bioenergetic components (inorganic phosphate and creatine) are determined by regulated transcellular transport processes. During recovery after exercise the kinetics and control of mitochondrial ATP synthesis can be established. During exercise the relative contributions to ATP synthesis of phosphocreatine (using creatine kinase), anaerobic glycogenolysis and oxidative phosphorylation are dissected and have been shown to change with time. The consequences of mitochondrial lesions and dysfunctions on these processes have been summarised.

Topics: Adenosine Triphosphate; Energy Metabolism; Humans; Ischemia; Kinetics; Magnetic Resonance Spectroscopy; Mitochondria; Mitochondrial Myopathies; Phosphocreatine; Reference Values; Renal Dialysis; Uremia

31P Nuclear magnetic resonance (NMR) spectroscopy of the tibialis anterior muscle was carried out on nine acutely ischaemic limbs in eight patients before and after revascularization, in 15 limbs of 13 claudicants at rest, in 17 patients with normal lower limb circulation suffering chronic renal failure, and in six healthy subjects. Claudicants, renal failure and healthy limbs showed similar inorganic phosphate/phosphocreatine ratios (Pi/PCr). Healthy volunteers after 30-min tourniquet ischaemia and patients with acutely ischaemic limbs showed significantly raised Pi/PCr ratios (P < 0.05). There was an association between Pi/PCr ratios and the systolic ankle:brachial pressure index in acutely ischaemic limbs. In the acute patients, the Pi/PCr ratios returned to normal after successful revascularization, the time course varying between 3 days and 3 months. Intracellular acidosis was observed in one patient who was also the only individual to develop reperfusion injury following reconstructive surgery. Acidosis may be a sign of muscle changes which lead to reperfusion injury.

Topics: Adult; Aged; Aged, 80 and over; Energy Metabolism; Female; Hemodynamics; Humans; Ischemia; Leg; Magnetic Resonance Spectroscopy; Male; Middle Aged; Muscle, Skeletal; Phosphates; Phosphocreatine; Postoperative Complications; Reference Values; Thrombosis

A surgical method is described which allows in vivo assessment of reversible rat pancreatic ischemia using 31P NMR spectroscopy at 2.0 T. Phosphorous-31 NMR spectra acquired during the ischemic period show the expected increase in inorganic phosphate with a concomitant decrease in ATP levels and pH as compared to controls. Upon reperfusion, inorganic phosphate and ATP returned to control levels while pH recovered to a more alkaline value. This method provides a means of studying in vivo changes in high energy metabolite associated with acute pancreatitis (AP) and maintains the secretory ability of the gland so that different forms of AP, such as those arising from pancreatic juice edema, can be studied.

Topics: Adenosine Triphosphate; Animals; Female; Hydrogen-Ion Concentration; Ischemia; Magnetic Resonance Spectroscopy; Pancreas; Phosphates; Phosphocreatine; Rats; Rats, Sprague-Dawley

The role of O2 delivery in regulating VO2max has been studied in an isolated gastrocnemius-plantaris muscle preparation contracting in situ; recent data addressing this issue are presented. VO2 increases nonlinearly with stimulation frequency reaching a peak at 5 twitches.s-1 or 1 tet.s-1 (200 ms trains, 50 imp.s-1). Further increases in stimulation frequency result in a lower VO2. Measured VO2 maxima are less than predicted VO2 capacity, and peak VO2 during tetanic contractions is greater than that during twitches. Above 150 imp.min-1, VO2 is directly related to the level of blood flow attained as VO2/Q (arterial-venous O2 difference) is fixed by some unknown mechanism. Increasing blood flow, with a pump, during 1.s-1 tetanic contractions increases O2 diffusive conductance and peak VO2. When O2 delivery is reduced, ischemic hypoxia appears to result in more rapid reductions in muscle performance than hypoxic hypoxia because of decreases in perfusion pressure and Q. 31P-NMR studies reveal that reductions in creatine phosphate and energy charge are similar between ischemia and hypoxia suggesting a common regulator, O2. We conclude that VO2max is limited by O2 delivery as a result of a limited and uneven distribution of muscle blood flow. These limitations appear secondary to mechanical restraints imposed by contraction duty cycle and vascular compression.

Topics: Animals; Blood Pressure; Dogs; Electric Stimulation; Energy Metabolism; Hyperemia; Hypoxia; Ischemia; Isometric Contraction; Isotonic Contraction; Magnetic Resonance Spectroscopy; Muscle Contraction; Muscle Fibers, Skeletal; Muscle, Skeletal; Oxygen; Oxygen Consumption; Phosphocreatine; Phosphorus Isotopes; Regional Blood Flow

Topics: Adenosine Triphosphate; Animals; Cytosol; Dogs; Energy Metabolism; Glycolysis; Hemoglobins; Ischemia; Mitochondria, Muscle; Models, Biological; Muscle, Skeletal; Myoglobin; Oxidation-Reduction; Oxygen Consumption; Phosphocreatine

We have used a rectangular surface coil and chemical shift imaging to conduct in vivo localized 31P NMR metabolic studies in a rat dorsal skin flap model. This approach permits regional comparisons without manipulation of either coil position or subject within the magnet bore. Both the PCr:Pi ratio (reflecting ischemia insult) and the PCr:ATP ratio (reflecting phosphagen reserves) decreased as functions of time and distance from the vascular pedicle. The maximum change was nearly 6-fold for the PCr:Pi ratio, and 3-fold for the PCr:ATP ratio. Signal contamination from subjacent muscle is constant and does not interfere with the metabolic evaluations of skin flaps. This technique may facilitate a better understanding of cutaneous metabolic derangements, such as burns and skin flaps used in reconstructive surgery, as well as studies of pharmacologic regimens developed for their treatment. It also holds potential for application in the study of congenital and neoplastic metabolic disorders of skin.

Topics: Adenosine Triphosphate; Animals; Burns; Energy Metabolism; Hempa; Ischemia; Magnetic Resonance Spectroscopy; Male; Models, Structural; Muscle, Skeletal; Phosphates; Phosphocreatine; Phosphorus Isotopes; Rats; Rats, Sprague-Dawley; Skin; Skin Diseases; Skin Neoplasms; Surgical Flaps; Time Factors

The effect of 'simulated ischemia', i.e., combined anoxia and substrate deprivation, was studied in 1- and 3-week-old (i.e., immature and mature) primary cultures of mouse astrocytes. Cell survival, as indicated by retention of the high-molecular cytosolic protein lactate dehydrogenase was compared with retained high-energy phosphate compounds (ATP and phosphocreatine). A previously established longer survival of the immature cells during the metabolic insult was confirmed and found to correlate with a more complete maintenance of high-energy phosphates. However, in both the mature and immature cells, no death occurred as long as the ATP content remained at or above 25% of its control value. ATP concentrations below 10% of control were accompanied by almost complete cell death in both age groups. Thus, the better survival of immature astrocytes during simulated ischemia is correlated with better maintenance of the levels of high-energy phosphates and, regardless of age, cell death occurs only once a critically 'low' threshold of ATP has been reached.

Topics: Adenosine Triphosphate; Analysis of Variance; Animals; Animals, Newborn; Astrocytes; Cell Hypoxia; Cells, Cultured; Cellular Senescence; Energy Metabolism; Ischemia; Kinetics; L-Lactate Dehydrogenase; Mice; Phosphocreatine; Time Factors

Phosphoenergetic and pH images in human calf muscles before and after ischemic exercise were generated by 31P NMR chemical shift imaging (CSI) with a 1.5 T standard clinical MR machine using a home-built volume coil. Acquisition of data was repeated four times with 8 x 8 phase-encoding steps and 1 s repetition time. The total acquisition time was 4 min 16 s. After 3-dimensional (3D) Fourier transformation with zero-filling, 2-dimensional (2D) images with 32 x 32 matrices of phosphocreatine (PCr), inorganic phosphate (Pi), PCr/(PCr + Pi) and pH were constructed. These metabolic images were overlaid with concurrently observed 1H MRI to locate the areas showing metabolic response. After 3 min exercise consisting of repeated plantarflexion of the foot under ischemic conditions, decreases in phosphoenergetic levels and acidosis were the most severe in the peroneus muscles, moderate in the tibialis anterior muscle, and slight in the triceps muscle of the calf. Under maintained ischemic conditions, phosphoenergetic level further decreased, but the acidosis in each muscle did not progress further. Heterogeneous metabolic and pH changes throughout the entire calf muscle were clearly demonstrated in detail by these images.

Topics: Acidosis; Adult; Energy Metabolism; Fourier Analysis; Humans; Hydrogen-Ion Concentration; Image Processing, Computer-Assisted; Ischemia; Leg; Magnetic Resonance Spectroscopy; Male; Middle Aged; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal; Phosphates; Phosphocreatine; Phosphorus Isotopes; Physical Exertion

To clarify the role of thromboxane A2 synthetase inhibitor (CV-4151) in the ischemia-reperfusion injury, the effect of CV-4151 was investigated in the gastrocnemius muscles of female Lewis rats. All tissues except femoral vessels were transected at the midthigh level and 4 h of ischemia was induced by vascular clamping of the femoral artery and vein, followed by 1 h of reperfusion. The sham group (n = 8) underwent the operation without ischemia-reperfusion; the control group (n = 8) with ischemia-reperfusion, and the CV-4151 group (n = 8) was pretreated with CV-4151 20 mg/kg. Skeletal muscle blood flow was measured by a hydrogen gas clearance method; the blood flow restored fully in the CV-4151 group, while it remained significantly low in the control group after 1 h of reperfusion (p < 0.05). Tissue levels of adenosine triphosphate (ATP) and creatine phosphate (PCR) were measured after 1 h of reperfusion; ATP decreased to 25% of nonischemic values in the control group. In contrast, premedication with CV-4151 significantly improved the recovery of ATP (p < 0.01). PCR showed the same tendency as ATP; CV-4151 also improved the recovery of PCR significantly (p < 0.05), but CV-4151 did not prevent the production of lipid peroxides. Serum thromboxane B2 was determined by radioimmunoassay; in the sham and the CV-4151 group the level was significantly lower than in the control group (p < 0.05). was significantly lower than in the control group (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adenine Nucleotides; Adenosine Triphosphate; Animals; Fatty Acids, Monounsaturated; Female; Ischemia; Lipid Peroxides; Muscles; Phosphocreatine; Pyridines; Rats; Rats, Inbred Lew; Regional Blood Flow; Reperfusion; Thromboxane B2; Thromboxane-A Synthase

Topics: Adenine Nucleotides; Allopurinol; Animals; Energy Metabolism; Ischemia; Muscle Contraction; Muscles; Phosphocreatine; Rats; Rats, Wistar

In order to assess the acute metabolic effects of an intra-arterial infusion of nucleotide-nucleoside-mixture (NNM), 31P-mr-spectroscopy at the site of m. gastrocnemius and metabolite determinations from blood of the femoral artery and vein were carried out in 10 patients with PAOD stage II during ergometric calf exercise to the claudication pain limit. The spectroscopic measurements revealed a greater exercise-induced fall of PCr and a higher increase of Pi in calf muscles during supply of NNM compared with control ergometry. Post-exercise recovery of PCr was distinctly delayed during infusion of NNM. The anaerobic production of energy, however, was sufficient to maintain the ATP concentration to the same extent as under control ergometry. On the other hand, intramuscular lactate acidosis developed to a lower degree with NNM infusion than without NNM. A reduced muscular release of lactate, pyruvate, ammonia and alanine followed from the evaluation of the arteriovenous balance of these metabolites in the femoral vessels indicating a favourable global metabolic effect of NNM infusion in the extremity. The apparent contradiction in the spectroscopic and analytic-biochemical findings can be explained by local blood shunts induced by maximum vasodilation. Noninvasive mr-spectroscopy allows to detect directly and continuously the metabolic impact of ischemia in the calf muscles afflicted by arterial occlusion, whereas the metabolite concentrations in femoral blood are altered by afflux from non-ischemic areas. The known clinical benefit of frequently repeated intra-arterial infusions of NNM is thought to be due to an expansion of collateral circulation and to a favourable influence on endothelial functions.

Topics: Adenosine Triphosphate; Arterial Occlusive Diseases; Energy Metabolism; Exercise Test; Humans; Infusion Pumps; Intermittent Claudication; Ischemia; Leg; Magnetic Resonance Spectroscopy; Male; Muscles; Nucleosides; Nucleotides; Phosphates; Phosphocreatine

There are no data concerning the functional or metabolic effects of hypoxia in vivo in smooth muscle. We have therefore used 31P-NMR spectroscopy and intra-uterine pressure measurements to examine simultaneously, in vivo, the effect of ischaemia on uterine metabolites, intracellular pH (pHi) and force. A 1-2 cm portion of uterus from day 1 postpartum anaesthetized rats was exteriorized and an NMR surface coil placed on it. A balloon catheter in the uterine lumen recorded intra-uterine pressure changes from the same area. Reversible occluders were placed around the uterine artery. Occlusion produced a decrease and then abolition of contractions, within 10 min. In four of five animals contraction was abolished within 2 min. Upon reperfusion force was rapidly restored (1 min), in all preparations. The mean level of force was significantly above control (pre-occlusion) 20-30 min after reperfusion. The NMR data showed a significant fall in [ATP] (28%) and [phosphocreatine] (34%) during occlusion. Inorganic phosphate doubled in concentration during this period. Metabolites recovered slowly upon reperfusion, taking 20-30 min to return to pre-occlusion levels. The mean pHi fell from 7.32 to 7.00 upon occlusion and was rapidly reversed upon reperfusion. The changes in pHi closely correlated with the changes in uterine force. Decreases of pHi of a similar magnitude in vitro have previously been shown to abolish contractions; thus it is suggested that during ischaemia in vivo the depression of contraction is caused by the large fall in pHi.

Topics: Animals; Female; Hydrogen-Ion Concentration; Hypoxia; In Vitro Techniques; Ischemia; Magnetic Resonance Spectroscopy; Muscle, Smooth; Phosphates; Phosphocreatine; Rats; Rats, Wistar; Regional Blood Flow; Uterine Contraction; Uterus

Glucagon is a potent mesenteric vasodilator, inotrope, and stimulant of intestinal metabolism that enhances survival when given during reperfusion after intestinal ischemia. However, the mechanism of improved survival is unclear and may be due to systemic hemodynamic effects rather than intestinal metabolic changes. We examined the effects of glucagon on intestinal energy metabolism during reperfusion after intestinal ischemia. Sprague-Dawley rats were subjected to 50 min intestinal ischemia by clamping the superior mesenteric artery. All received 10 ml/kg.hr 5% glucose in normal saline for 3 hr. One group (n = 17) received 1.6 micrograms/kg.min glucagon for 2 hr beginning at reperfusion. Control rats (n = 10) received only vehicle. Jejunal biopsies preischemia, end ischemia, 10, 20, 45, 80 min, and 24 hr after reperfusion were analyzed for ATP, ADP, and AMP. ATP decreased more than 60% with ischemia and recovered substantially in all animals by 10 min postischemia. ATP recovered steadily in control rats and by 24 hr was not distinguishable from baseline. In contrast, in glucagon-treated rats, ATP decreased at 20 and 45 min during reperfusion, but recovered incompletely by 24 hr after ischemia. Energy charge (EC = ([ATP] + 1/2[ADP]) divided by ([ATP] + [ADP] + [AMP])) decreased during ischemia but recovered immediately after reperfusion in both groups, implying that energy was available, energy metabolic enzyme systems were at least partially intact, and immediate recovery was not limited by available substrate and blood flow. However, energy charge decreased slightly during glucagon infusion, suggesting increased utilization of energy or some derangement of energy metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Energy Metabolism; Female; Glucagon; Intestinal Mucosa; Intestines; Ischemia; Male; Phosphocreatine; Rats; Rats, Sprague-Dawley; Reperfusion

The influence of graded leg muscle ischaemia on the adaptation to training and on the acute response to exercise was studied in healthy subjects. Graded ischaemia during supine exercise was induced by application of 50 mmHg external pressure on the legs. This procedure reduced leg blood flow by 16%, venous oxygen saturation by 12 percentage units, and markedly increased lactate release (p < 0.05 for all). One-legged training was performed during four weeks, 4 sessions per week. Each session started with one leg training for 45 min with reduced blood flow (ischaemic training). The contralateral leg, serving as a control, was then trained with an identical power-output profile for 45 min but without flow restriction (non-ischaemic training). Ischaemic training enhanced the adaptation to training. Peak oxygen uptake and time to fatigue increased more (p < 0.05) with ischaemic than with non-ischaemic training. Citrate synthase activity, capillaries per fibre, and glycogen content were greater (p < 0.05) in the trained than in the detrained state. In the ischaemically trained leg, the type IIb fibre proportion was lower (p < 0.05) and the I fibre proportion tended to be higher (p = 0.06) in the trained than in the detrained state. Maximum voluntary dynamic strength was decreased by 8% (p < 0.01) in the ischaemically trained leg, but was unaffected in the non-ischaemically trained leg. During acute ischaemic exercise, as compared to non-ischaemic exercise, there was a higher degree of glycogen depletion, a greater depletion of type II, but not of type I fibres, a greater electromyographic activity, higher catecholamine concentrations, lower intramuscular ATP and creatine phosphate content, and an increased nitric oxide formation as estimated by increased plasma nitrate content. In conclusion, the mechanisms underlying the potentiation of the adaptation to training by ischaemia are assumed to depend on the operation of stimuli which were amplified during acute ischaemic exercise.

Topics: Acute Disease; Adaptation, Physiological; Adenosine Triphosphate; Adolescent; Adult; Biopsy; Blood Flow Velocity; Blood Gas Analysis; Capillaries; Catecholamines; Citrate (si)-Synthase; Electromyography; Exercise Therapy; Glycogen; Humans; Ischemia; Lactates; Lactic Acid; Leg; Male; Models, Cardiovascular; Muscles; Nitric Oxide; Oxygen; Oxygen Consumption; Phosphocreatine

The heat-shock response refers to specific reversible changes in cellular metabolism that impart a protective effect on individual cells, as well as entire organisms, against subsequent noxious stimuli. Our objective was to quantify skeletal muscle injury following an ischemic event in a rat model by measuring levels of adenosine triphosphate and creatine phosphate. The animals were divided into two experimental groups. Animals in group 1 (n = 15) were subjected to limb ischemia alone, and animals in group 2 (n = 15) were treated with heat-shock conditioning prior to the onset of ischemia. Skeletal muscle specimens also were examined ultrastructurally by electron microscopy. Levels of creatine phosphate were higher in skeletal muscle obtained from animals in group 2. Mean levels of creatine phosphate +/- SEM for groups 1 and 2 were 1.12 +/- 0.06 mumol/gm and 1.95 +/- 0.11 mumol/gm, respectively (p < 0.0001). This represents 18.4 and 31.9 percent of baseline nonischemic levels for groups 1 and 2, respectively (p < 0.0001). Adenosine triphosphate levels were measured in skeletal muscle samples from a subset of animals in each experimental group, group 1 (n = 6) and group 2 (n = 5), and were not significantly different. Electron microscopy demonstrated mitochondrial changes consistent with ischemic injury in group 1, but only nonspecific changes were noted in specimens from group 2. The presence of the primary 72-kDa heat-shock protein (HSP 72) was confirmed only in those animals treated by heat-shock conditioning. We conclude that prior stress conditioning using the heat-shock response confers significant biochemical and ultrastructural protection against ischemic injury in rat skeletal muscle.

Topics: Adenosine Triphosphate; Animals; Heat-Shock Proteins; Ischemia; Male; Microscopy, Electron; Muscles; Phosphocreatine; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Stress, Physiological

Using 31P nuclear magnetic resonance spectroscopy of the calf muscle, the authors studied patients with peripheral arterial occlusive disease. They studied PCr depletion and intracellular pH during aerobic exercise in patients and controls. The phosphocreatine (PCr) index ([PCr]/([PCr] + [Pi])) at rest was correlated with blood flow measured by plethysmography. During aerobic exercise a greater decrease in pH was obtained in patients (p < 0.03). They also studied the work necessary to reach a PCr index = 0.5 during ischemic exercise. This workload was lower in patients than in controls: 32.99 +/- 3.04 J vs 58.89 +/- 8.55 J, p < 0.05. After vasodilator therapy the workload was improved in patients: 32.99 +/- 3.04 J vs 38.85 +/- 3.54 J, p < 0.05. These results suggest that therapy resulted in improved tissue perfusion in patients.

Topics: Arterial Occlusive Diseases; Exercise; Humans; Hydrogen-Ion Concentration; Intermittent Claudication; Ischemia; Leg; Magnetic Resonance Spectroscopy; Middle Aged; Oxidative Phosphorylation; Phosphocreatine; Phosphorus Radioisotopes; Vasodilator Agents

1. The chemical changes during contractile activity were separated from recovery metabolism in the forearm flexor musculature in normal human subjects using 31P nuclear magnetic resonance (NMR) spectroscopy. Percutaneous, supramaximal twitch stimulation of the median and ulnar nerves was used in combination with temporary ischaemia of the forearm to characterize the summed ATPase activity. The recovery following restoration of blood flow provided a measure of oxidative ATP synthesis activity. These processes were measured based on the dynamics of creatine phosphate (PCr) content. 2. Muscle oxygen stores were depleted using ischaemia without stimulation as indicated by PCr breakdown after 250 +/- 33 s (mean +/- S.D.; n = 5), which provided a measure of the basal metabolic rate (0.008 +/- 0.002 mM s-1, n = 5). 3. The PCr breakdown rate during twitch stimulation of the oxygen-depleted muscle was constant at 1 Hz at 0.15 +/- 0.03 mM PCr per second or per twitch (n = 8). A constant cost per twitch was found from 0.5 to 2 Hz stimulation (depletion of PCr per twitch = 0.15 mM per twitch). 4. No net anaerobic recovery of PCr was found during a 2 min post-stimulation ischaemia. 5. Upon restoration of blood flow, PCr recovery followed an exponential time course with a time constant of 63 +/- 14 s (n = 8). From these recovery rates, the capacity for oxidative phosphorylation was estimated to be 0.4 mM s-1. 6. This experimental approach defines a non-invasive and quantitative measure of human muscle ATPase rate and ATP synthetase rate.

Topics: Adenosine Triphosphatases; Adenosine Triphosphate; Adult; Aerobiosis; Electric Stimulation; Electromyography; Energy Metabolism; Exercise; Female; Forearm; Humans; Hypoxia; Ischemia; Male; Middle Aged; Muscles; Oxygen Consumption; Phosphocreatine; Regional Blood Flow

Non-localized and localized 31P nuclear magnetic resonance (NMR) spectra of rat calf muscle during arterial occlusion and after reperfusion were concurrently observed using chemical shift imaging and 1H magnetic resonance imaging (MRI). During ischaemia, the levels of high-energy phosphates (phosphocreatine and adenosine 5'-triphosphate) were depleted and that of inorganic phosphate was increased. In addition, the signal intensity on 1H MRI was increased. These changes were observed to be relatively homogeneous throughout the calf. In contrast, the changes during reperfusion were heterogeneous. In the central part of the calf, inorganic phosphate disappeared, phosphocreatine was restored immediately on reperfusion and the 1H signal was decreased. However, in the regions of the tibialis anterior muscle and the superficial part of the gastrocnemius muscle, inorganic phosphate persisted for several hours, phosphocreatine was not restored and the signal intensity on T2-weighted 1H MRI was increased further. The heterogeneous changes detected by 31P NMR spectroscopy and 1H MRI showed close agreement. The susceptibility of different calf muscles to ischaemia and reperfusion seems to depend on their predominant muscle fibre type (i.e. fast-twitch or slow-twitch fibres). Reversible and irreversible ischaemic changes could be non-invasively distinguished by in vivo 31P NMR spectroscopy and 1H MRI.

Topics: Adenosine Triphosphate; Animals; Energy Metabolism; Ischemia; Magnetic Resonance Spectroscopy; Male; Muscles; Phosphates; Phosphocreatine; Rats; Rats, Wistar; Reperfusion Injury; Water-Electrolyte Balance

The perfused rat hindlimb preparation was used with a blood cell-free perfusate to investigate alterations in the purine nucleotide metabolism, flow rate, perfusion pressure, and venous excretion in response to ischemia and ischemia followed by reperfusion in skeletal muscle. The development of a physical hindrance during postischemic reperfusion, indicated by an increase in reperfusion pressure and a decrease in flow rate, coincided with a 90% decrease in phosphocreatine and a 50-70% reduction in total adenine nucleotide pool. The reflow impairment could not be explained by blood cell plugging of the capillaries. Washout of several metabolites was demonstrated during reperfusion. Hypoxanthine accumulated intracellularly during ischemia, and a substantial amount of uric acid was excreted into the venous effluent during reperfusion. The experimental data were fitted into a computer simulation model of the purine pathways. The model indicated that AMP deaminase was the predominant enzymatic pathway for the AMP degradation. It was demonstrated that ATP preferably accumulated as inosine-5'-monophosphate during ischemia and that xanthine oxidase was undetectable in skeletal muscle tissue homogenates. However, vascular endothelial cell xanthine oxidase activity responsible for a free radical-induced reperfusion injury could not be excluded.

Topics: Adenine Nucleotides; Animals; Computer Simulation; Female; Hindlimb; Inosine Monophosphate; Ischemia; Models, Biological; Muscles; Perfusion; Phosphocreatine; Purine Nucleotides; Rats; Rats, Sprague-Dawley; Reperfusion; Xanthine Oxidase

Creatine kinase (CK) is normally found at high levels in muscle and brain and catalyzes the reaction phosphocreatine (PCr) + MgADP + H+<==>creatine (Cr) + MgATP. CK is not normally found at high levels in liver. A line of transgenic mice that express high levels of the BB-dimer of CK (CKB) in liver has allowed us to assess the role of CKB during periods of low oxygen stress. During 40 min of ischemia of normal perfused livers at 25 degrees C, ATP levels are depleted, and pH decreases to 6.6. pH recovers to a preischemic level after 30 min of reperfusion of normal livers; however, P(i) levels are significantly higher and ATP levels significantly lower than preischemic values. In transgenic liver with an initial PCr-to-ATP ratio of 4.5, ATP levels are maintained until PCr is markedly depleted. pH remains at preischemic levels for 16 min of ischemia of transgenic livers. During this length of ischemia in normal livers, pH has dropped to 6.9. pH, P(i), and ATP levels return to preischemic values within 30 min of reperfusion in transgenic livers containing PCr and CK. During 90 min of hypoxia of normal perfused livers at 37 degrees C, ATP is depleted. After 15 min of hypoxia of normal livers, there is a significant increase in the release of lactate dehydrogenase (LDH). In transgenic livers, ATP is maintained, and no increase in LDH release is observed for up to 90 min, depending on the level of PCr before hypoxia. These results demonstrate the role of CKB in buffering ATP levels and regulating intracellular pH during periods of low oxygen stress.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adenosine Triphosphate; Animals; Creatine Kinase; Hydrogen-Ion Concentration; Hypoxia; Ischemia; Isoenzymes; Kinetics; L-Lactate Dehydrogenase; Liver; Liver Glycogen; Magnetic Resonance Spectroscopy; Mice; Mice, Inbred Strains; Mice, Transgenic; Phosphocreatine; Reperfusion; Time Factors

To examine the action of alpha-tocopherol on high energy phosphate compounds, a 31P-NMR technique was applied to perfused Langendorff rat hearts. Rats were treated with tocopherol acetate (25 mg/kg body wt i.p.) for 7 consecutive days. On the 7th day, the rat hearts were isolated for the Langendorff experiment. After 30 min of global ischemia the NMR signals of creatine phosphate and ATP in myocardium disappeared, and then recovered slightly in the reperfusion following ischemia. However, in the tocopherol-treated rat hearts, the restoration of high energy phosphate compounds occurred quickly after the beginning of reperfusion, although there was no significant difference in the destruction of high energy phosphate compounds during the ischemia. The alpha-tocopherol level in the myocardium was severely depleted by ischemia-reperfusion. In the alpha-tocopherol-treated animals, the alpha-tocopherol level in myocardium was still significantly higher than the control level at the end of 30 min of global ischemia. The heart mitochondrial respiratory function was simultaneously protected against ischemia-reperfusion injury. The role of alpha-tocopherol was discussed as a radical scavenger and membrane stabilizer against oxygen stress.

Topics: Adenine Nucleotides; Animals; Heart; Hydrogen-Ion Concentration; Ischemia; Magnetic Resonance Spectroscopy; Male; Mitochondria, Heart; Myocardium; NAD; Phosphocreatine; Rats; Rats, Wistar; Reperfusion Injury; Vitamin E

The ischemia tolerance of free-muscle flaps was investigated in the rat by orthotopic and syngeneic transplantation of muscle flaps measuring 4 x 2.5 cm. The effects of ischemia with a maximal duration of 7 hours on the raised flaps and of anoxia caused by occlusion of the flap vessels were studied for the first time using 31P-spectroscopy. Energy metabolism was found to recover fast after 3 hours of ischemia, whereas a duration of 4 hours led to severe, only slowly reversible changes. Longer periods of ischemia resulted in a complete loss of energy reserves (PCr) and weaker ATP signal. The complete absence of ATP and a pH value under 6 indicated irreversible muscular damage.

Topics: Abdominal Muscles; Adenosine Triphosphate; Anastomosis, Surgical; Animals; Energy Metabolism; Femoral Artery; Femoral Vein; Glucosephosphates; Hydrogen-Ion Concentration; Ischemia; Magnetic Resonance Spectroscopy; Male; Muscles; Phosphates; Phosphocreatine; Rats; Rats, Inbred Lew; Reperfusion; Surgical Flaps; Thrombosis; Time Factors

The purpose of this study was to characterize twitch tension and energy metabolism in ischemic, stimulated rat hindlimb to determine its suitability as a rapid time course model of ischemia-reperfusion injury. After 15 min equilibration, rat hindlimbs were stimulated (1-Hz twitches, 0.2 ms pulse duration, 15 V) for 5 min (control, n = 8). This twitch protocol was maintained throughout the ischemic and reperfusion periods. The control period was followed by 5, 20, or 40 min of ischemia (ligation of femoral artery and vein) or 40 min of ischemia with 0, 5, or 20 min of reperfusion (removal of ligature). The soleus [89% slow oxidative (SO)] and the white gastrocnemius [WG; 91% fast glycolytic (FG)] were analyzed for phosphocreatine (PCr), adenine nucleotides, glycogen, and glycolytic intermediates. Ischemia was characterized by progressive decreases in twitch tension, high-energy phosphagens, total adenine nucleotides (TAN), and glycogen. Also, energy metabolism was altered at a greater rate in WG than in soleus. Reperfusion resulted in a recovery in PCr and lactate, with little change in ATP, TAN, or glycogen. The inability to resynthesize adenine nucleotides and glycogen during reperfusion is characteristic of damaged skeletal muscle. The extent of the metabolic alterations in SO and FG muscles during twitch stimulation was comparable with previously reported noncontracting ischemia protocols of 2-4 and 4-7 h in length, respectively. The present study demonstrates that twitch stimulation of ischemic skeletal muscle is a useful model for inducing rapid metabolic changes and an ischemic insult comparable to prolonged noncontracting ischemia-reperfusion models.

Topics: Adenine Nucleotides; Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Electric Stimulation; Energy Metabolism; Hexosephosphates; Hindlimb; Ischemia; Kinetics; Lactates; Male; Muscle Contraction; Muscles; NAD; Phosphocreatine; Pyruvates; Rats; Rats, Sprague-Dawley; Reperfusion; Time Factors

Changes in the metabolites phosphocreatine (PCr), Pi and ATP were quantified by 31P n.m.r. spectroscopy in the human calf muscle during isometric contraction and recovery under ischaemic conditions. Time resolution of the measurements was 10 s. During a 30-60 s ischaemic isometric contraction, PCr decreased linearly at a rate of 1.17%/s (relative to the resting value) at a contraction strength equivalent to 70% of the maximal voluntary contraction (MVC) and at a rate of 2.43%/s at 90% MVC. There was a corresponding increase in Pi but the concentration of ATP did not change. pH decreased linearly during contraction by 4.22 and 8.23 milli-pH units/s at 70 and 90% MVC respectively. During a subsequent 5 min interval of ischaemic recovery, PCr, Pi, ATP, phosphomonoesters and calculated free ADP, free AMP and pH retained the value they had attained by the end of contraction with no significant recovery. Thus it is concluded that anaerobic glycolysis and glycogenolysis is halted momentarily on termination of contraction and that PCr is not resynthesized during ischaemic recovery. This paradoxical arrest of glycolytic flow in spite of the very significantly elevated concentration of potent activators such as Pi and free AMP clearly indicates that parameters other than PCr, ATP, Pi, calculated pH, free ADP and free AMP regulate glycolysis and glycogenolysis of human skeletal muscle very efficiently under ischaemic conditions.

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Adult; Glycogen; Glycolysis; Humans; Hydrogen-Ion Concentration; Ischemia; Isometric Contraction; Kinetics; Magnetic Resonance Spectroscopy; Male; Muscles; Phosphates; Phosphocreatine

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

We obtained 202.5-MHz 31P-nuclear magnetic resonance (NMR) spectra of isolated perfused rat lungs, degassed and inflated, and of lung extract. The spectra included those of ATP, ADP, phosphocreatine (PCr), inorganic phosphate (Pi), phosphomonoesters, phosphodiesters, and a broad component due to the membrane phospholipids. The line width at one-half peak height for beta-ATP was 1.0 ppm for the degassed lung and 1.2 ppm for the inflated lung. This suggests that the air-water interfaces in inflated lung, which produce proton NMR line broadening, do not act prominently in 31P-NMR spectroscopy. In a degassed lung, when perfusion was stopped for up to 30 min, PCr and ATP peaks decreased progressively with time while Pi and phosphomonoester peaks increased. On return of flow, these changes reversed. The intracellular pH values calculated from the difference in magnetic field between PCr and Pi peaks of inflated and degassed lungs were 7.16 +/- 0.10 (SD; n = 4) and 6.99 +/- 0.10 (n = 4), respectively. The change of intracellular pH caused by 30 min of ischemia was -0.2 pH units. Our findings indicate that air-water interfaces should not broaden lung 31P peaks in vivo.

Topics: Adenosine Triphosphate; Animals; Hydrogen-Ion Concentration; In Vitro Techniques; Ischemia; Lung; Magnetic Resonance Spectroscopy; Membrane Lipids; Perfusion; Phosphates; Phosphocreatine; Phospholipids; Rats

The sensitivity of in vivo MRS of the N-delta proton of the proximal histidine of deoxymyoglobin in human skeletal muscles is discussed. Longitudinal relaxation time T1 of this deoxymyoglobin signal was measured in cuffed human forearms at 1.5 T and found to be 9.9 ms. Deoxymyoglobin spectra can be obtained from a forearm in seconds. The detection sensitivity of deoxymyoglobin in fully ischemic skeletal muscles and that of 31P MRS of PCr in normal resting muscles are compared.

Topics: Adult; Animals; Cattle; Female; Forearm; Histidine; Humans; Ischemia; Magnetic Resonance Spectroscopy; Male; Muscles; Myocardium; Myoglobin; Phosphocreatine; Phosphorus; Protons

The effect of ischemia on atrial natriuretic peptide (ANP) release from heart ventricles was studied by exposing the perfused hearts of Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats to global ischemia after excision of the atria. Ischemia for 2, 5 and 20 min caused an increase of 0.3 +/- 1.1, 12.4 +/- 5.5 and 11.4 +/- 4.2 ng/g dry weight in ANP release of the WKY ventricles, respectively. ANP release increased 3.4 +/- 2.8 ng/g dry weight after 5 minutes' ischemia from the SHR ventricles. The increase was not caused by cell damage, as only processed form of the peptide was detected in the perfusates. The increase in ANP release in the WKY ventricles correlated positively with the tissue lactate/pyruvate ratio (r = 0.85) and adenosine (r = 0.99), and negatively with the phosphorylation potential (r = -0.70). The results indicate that ventricular ischemia increases ANP release, probably due to changes in myocardial energy metabolism.

Topics: Adenosine Triphosphate; Animals; Atrial Natriuretic Factor; Energy Metabolism; Heart Ventricles; Ischemia; Myocardial Contraction; Myocardium; Phosphocreatine; Rats; Rats, Inbred WKY

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

Skeletal muscle ischemia results in energy depletion and intracellular acidosis. Reperfusion is associated with impaired adenine nucleotide resynthesis, edema formation, and myocyte necrosis. The purpose of these studies was to define the time course of cellular injury and adenine nucleotide depletion and resynthesis in postischemic skeletal muscle during prolonged reperfusion in vivo. The isolated canine gracilis muscle model was used. After 5 h of ischemia, muscles were reperfused for either 1 or 48 h. Lactate and creatine phosphokinase (CPK) release during reperfusion was calculated from arteriovenous differences and blood flow. Adenine nucleotides, nucleosides, bases, and creatine phosphate were quantified by high-performance liquid chromatography, and muscle necrosis was assessed by nitroblue tetrazolium staining. Reperfusion resulted in a rapid release of lactate, which paralleled the increase in blood flow, and a delayed but prolonged release of CPK. Edema formation and muscle necrosis increased between 1 and 48 h of reperfusion (P less than 0.05). Recovery of energy stores during reperfusion was related to the extent of postischemic necrosis, which correlated with the extent of nucleotide dephosphorylation during ischemia (r = 0.88, P less than 0.001). These results suggest that both adenine nucleotide resynthesis and myocyte necrosis, which are protracted processes in reperfusing skeletal muscle, are related to the extent of nucleotide dephosphorylation during ischemia.

Topics: Adenine Nucleotides; Animals; Creatine Kinase; Dogs; Ischemia; Lactates; Lactic Acid; Muscles; Necrosis; Nitroblue Tetrazolium; Organ Size; Phosphocreatine; Regional Blood Flow; Reperfusion Injury; Time Factors

A modified crossover surface coil with minimal B1 field penetration was used for collection of skin phosphorus NMR spectra. Projection imaging experiments show that the coil-sensitive volume is uniform at the phosphorus frequency, but strikingly nonuniform at the proton frequency. Experiments with an in vitro phosphorus phantom, designed to simulate skin and underlying tissue, demonstrated that 45.1% (+/- 1.2%) of total signal was derived from Sprague-Dawley rat skin and 19.3% (+/- 1.4%) of total signal was derived from Fischer-344 rat skin. 31P MR spectra of rat skin in vivo permitted resolution of four phosphorus compounds: nucleoside triphosphates, phosphocreatine (PCr), inorganic phosphate (Pi), and phosphomonoester. Spectra collected after skin flap surgery in Fischer-344 rats showed a 50.1% (+/- 7.6%) reduction in the ratio of PCr/Pi within 30 min of surgery, compared to presurgical PCr/Pi levels (P less than 0.01). Skin phosphorus spectra are potentially useful for assessment of skin flap and skin graft viability.

Topics: Animals; Dermatologic Surgical Procedures; Equipment Design; Female; Hydrogen; Image Enhancement; Ischemia; Magnetic Resonance Spectroscopy; Models, Anatomic; Organophosphorus Compounds; Phosphates; Phosphocreatine; Phosphorus; Rats; Rats, Inbred F344; Rats, Inbred Strains; Skin; Surgical Flaps; Tissue Survival

Our model of severe nerve ischemia consistently results in extinction of the compound nerve and muscle action potentials (NAP; CMAP) within 30 min. Since impulse transmission may depend on nerve energy metabolism (NEM), we studied the effects of ischemia with reperfusion on sciatic-tibial nerve NEM in vivo and compared these results with NEM of this nerve in deoxygenated Ringer's solution in vitro and postmortem. Ischemia for 30 min postmortem or in deoxygenated Ringer's solution resulted in marked depletion of adenosine triphosphate (ATP) and creatine phosphate (CP) and an increase in lactate (LAC) of sciatic-tibial nerve of adult male Sprague-Dawley rats. In vivo ischemia for up to 3 h to sciatic-tibial nerve was sufficient to extinguish CMAP but not NAP and did not deplete ATP, CP, or GLU nor did it increase LAC. Ischemia sufficient to extinguish NAP resulted in reduction of energy substrates to about 50% of resting. Muscle fails to conduct impulses before nerve and in vivo reductions of energy substrates are milder than in vitro changes. These changes are explainable in terms of energy requirements and supply. These findings support an energetic basis of ischemic conduction failure.

Topics: Action Potentials; Adenosine Triphosphate; Animals; Energy Metabolism; Ischemia; Lactates; Male; Peripheral Nerves; Phosphocreatine; Rats; Rats, Inbred Strains; Reperfusion; Sciatic Nerve; Tibial Nerve

Renal failure often complicates endotoxin shock. This might be due to renal hypoperfusion, but endotoxemia could also have additional effects. We studied in anesthetized rats renal plasma flow (RPF), glomerular filtration rate (GFR), and metabolism (ATP, CrP = creatine phosphate, energy charge = [ATP + 0.5 ADP]/[ATP + ADP + AMP], lactate, glucose) during endotoxin shock (Escherichia coli endotoxin, 10 mg/kg for 60 min; n = 10) and "balloon shock" (balloon inflated in vena cava below renal vein to cause comparable decreases in cardiac output and RPF as in endotoxin-treated rats; n = 10). A third group of rats served as controls (n = 10). At t = 0 infusion of endotoxin was started. At t = 90 min, when cardiac output was low and serum lactate was high (indicating shock), GFR and RPF were obtained from plasma disappearance rates (from t = 90 to t = 135 min) of 125I-thalamate and 131I-hippurate, respectively. Experiments ended at t = 135 min. In both shock groups RPF decreased (by ca. - 75% compared with control rats), but filtration fraction only increased (by 72%) in the "balloon shock" rats. In renal biopsies lactate concentration increased more (by 407 vs. 167%) and ATP decreased more (by -63 vs. - 35%) during endotoxin shock than during "balloon shock"; the endotoxin-treated rats also showed a significant decrease in CrP (by - 58%), energy charge (by - 31%), and glucose concentration (by - 34%), and an increase in the number of leukocytes in the glomeruli (by 730%). Renal function and metabolism thus was more affected in this hypodynamic form of endotoxin shock than in "balloon shock." This may be caused by the effects of endotoxin on sticking of leukocytes and renal metabolism.

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Animals; Blood Glucose; Hemodynamics; Hippurates; Iothalamic Acid; Ischemia; Kidney; Lactates; Male; Phosphocreatine; Rats; Rats, Inbred Strains; Shock, Septic

Human heart preservation for transplantation commonly involves infusion of cold cardioplegic solutions and subsequent immersion in the same solution. The objectives of the present study were (1) to establish the temporal relationship between storage time (at 10 degrees C) and the postischemic recovery of function in the isolated rat heart, (2) to assess, by metabolic and functional measurements, whether storing the heart in fluid as opposed to moist air had any effect on the viability of the preparation, and (3) to ascertain the optimal storage temperature. Isolated rat hearts (at least 6 in each group) were infused for 3 minutes with St. Thomas' Hospital cardioplegic solution No. 2 at 10 degrees C, stored at 10 degrees C for 6, 12, 18, or 24 hours, and then reperfused at 37 degrees C. Mechanical function, assessed by construction of pressure-volume curves (balloon volumes: 20, 40, 60, 80, 100, and 120 microliters), was measured before ischemia and storage and after 60 minutes of reperfusion. Function deteriorated in a time-dependent manner; thus at a balloon volume of 60 microliters the recovery of left ventricular developed pressure was 84.2% +/- 5.3% after 6 hours (p = not significant when compared with preischemic control); 69.1 +/- 3.3% after 12 hours (p less than 0.05); 55.6% +/- 4.4% after 18 hours (p less than 0.05), and 53.0% +/- 6.8% (p less than 0.05) after 24 hours of storage. Other indices of cardiac function, together with creatine kinase leakage and high-energy phosphate content, supported these observations. Since the recovery of the left ventricular developed pressure balloon volume curves were essentially flat after 18 and 24 hours of storage, either 6 or 12 hours of storage were therefore used in subsequent studies. Comparison of storage environment (hearts either immersed in St. Thomas Hospital cardioplegic solution No. 2 or suspended in moist air at 10 degrees C for 6 or 12 hours) revealed no significant differences in functional recovery between the groups. Thus hearts recovered 94.9% +/- 3.5% and 113.7% +/- 12.4%, respectively, after 6 hours of storage and 71.6% +/- 2.4% and 54.2% +/- 7.9%, respectively, after 12 hours of storage. Enzyme leakage and tissue water gain were also similar in both groups of hearts. Finally, hearts (n = 6 per group) were subjected to 12 hours' storage at 1.0 degree, 5.0 degrees, 7.5 degrees, 10.0 degrees, 12.5 degrees, 15.0 degrees, and 20.0 degrees C.(ABSTRACT TRUNCATED AT 400 WORDS)

Topics: Adenosine Triphosphate; Air; Animals; Cardioplegic Solutions; Creatine Kinase; Humidity; In Vitro Techniques; Ischemia; Male; Mammals; Myocardium; Organ Preservation; Phosphocreatine; Rats; Temperature; Time Factors; Ventricular Function, Left

31P NMR spectra and 1H MR T1- and T2-weighted spin-echo images were concurrently observed in rat hind limb during arterial occlusion and following reperfusion. With arterial occlusion, phosphocreatine level decreased and inorganic phosphate (Pi) level increased in 31P NMR spectra. Intracellular pH's dropped as a function of time. Beta-ATP started to decrease in three hours. In six hours after the occlusion, any peaks other than Pi were scarcely detected. The signal intensities in the 1H MR images increased homogeneously in both T1- and T2-weighted conditions, but the changes were more profound with T2-weighted images. After the release of the arterial occlusion, the 31P NMR spectra recovered to the preischemic state in several hours. The 1H MR images during reperfusion showed characteristic heterogenous pattern. The signal intensities in the anterior tibial muscle and the gastrocnemius muscle remained high in T1-weighted condition and the intensities further increased in T2-weighted condition, while those in other parts returned to the preischemic level. These changes were found to be irreversible even 12 hr after the release. The high signal intensities suggested the increase of water in the extracellular compartment induced by so-called reperfusion injury. Multinuclear analysis using in vivo NMR was valuable to consecutively detect time-dependent and location-specific response in skeletal muscle during ischemia and reperfusion.

Topics: Adenosine Triphosphate; Animals; Hindlimb; Ischemia; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Male; Muscles; Phosphates; Phosphocreatine; Rats; Rats, Inbred Strains; Reperfusion

We studied the effects of rapid atrial pacing during the final 10 minutes of a 70-minute, 31% reduction in coronary blood flow in anesthetized swine to understand the significance of apparent metabolic improvements during the initial 60 minutes of segmental ischemia. Within 5-10 minutes of ischemia, subendocardial phosphocreatine (PCr) and ATP were depleted to 47% and 63% of control, respectively; lactate accumulated within the subendocardium to 300% of control; and net arteriovenous lactate production occurred. Despite continued ischemia and no significant changes in the external determinants of myocardial oxygen consumption, by 60 minutes subendocardial PCr and lactate contents returned to near control levels and there was net arteriovenous lactate consumption. Ischemic left ventricular wall thickening and ATP levels remained depressed throughout the experiment. Atrial pacing during the final 10 minutes of ischemia again resulted in depletion of PCr and lactate production. Since the myocardium was capable of hydrolyzing PCr in response to atrial pacing at 60 minutes of ischemia, we conclude it was capable of hydrolyzing PCr during the period of constant ischemia when instead it was accumulating PCr. We propose the ischemic myocardium downregulates regional energy requirements below blood flow-limited rates of energy production during ischemia. This appears to be an active adaptation to ischemia and not a result of passive damage or cellular injury.

Topics: Adaptation, Physiological; Adenosine Triphosphate; Animals; Coronary Circulation; Energy Metabolism; Female; Heart Rate; Hemodynamics; Ischemia; Lactates; Male; Myocardium; Oxygen Consumption; Phosphocreatine; Swine; Thermodynamics; Time Factors

Until now, the ischemic tolerance of muscle tissue has not been adequately understood. Even when muscle vitality is lost, the perfusion matrix of the muscle flaps is retained. Because of toxic decomposition, however, irreversibly damaged muscle cells almost certainly increase the rate of complications. The retention of the vitality of the transplanted muscle tissue is absolutely essential for the myokinetic substitute operations, currently in the development stage, involving the free transplantation of muscles. Investigations into vitality reserves were carried out on skeletal muscle specimens. Nuclear magnetic resonance spectroscopy was used to establish that, in ischemia, the ATP pool remained topped up to a large extent as long as phosphocreatine was available. As long as the ATP pool was retained, rearterialization led to the complete restoration of the essential preischemic metabolite concentrations. After the ATP had been exhausted, biochemical restitution through arterial reperfusion did not occur. The time by which the established vitality threshold was reached because of the loss of the ATP pool is called the critical ischemia time; it depends on muscle temperature. The critical ischemia time of human skeletal muscles was determined between 26 degrees and 38 degrees C. A normothermia of 34 degrees C yielded a critical ischemia time of 2.25 hours, which is shorter than that previously reported in the literature. An ischemic tolerance of 5 hours presupposes a muscle temperature of less than 26 degrees C.

Topics: Adenosine Triphosphate; In Vitro Techniques; Ischemia; Magnetic Resonance Spectroscopy; Muscles; Phosphates; Phosphocreatine; Surgical Flaps; Temperature; Tissue Survival

1. Using 31P nuclear magnetic resonance, it has previously been demonstrated that patients with congestive heart failure exhibit a greater than normal phosphocreatine (PCr) depletion in the working skeletal muscles of the arm. We have studied the importance of the work necessary to reach a similar PCr depletion ([PCr]/([PCr] + [Pi]) = 0.5) in calf muscle. Our results show significantly lower values for patients with congestive heart failure in both aerobic and ischaemic conditions (respectively: 0.009 +/- 0.007 vs 0.026 +/- 0.013 W/kg body weight, P less than 0.01; 0.29 +/- 0.16 vs 0.90 +/- 0.25 J/kg body weight, P less than 0.01). 2. This original model of skeletal muscle exercise facilitates a comparison of PCr recovery rate due to a similarity in the PCr depletion and intracellular pH in the two series at the start of recovery. However, the PCr recovery rate is similar after both normoxic and ischaemic exercise, i.e. respective percentages of PCr increase in the first 25 s recovery spectrum were: (a) aerobic exercise, congestive heart failure 133 +/- 18%, control series 138 +/- 18%; (b) ischaemic exercise, congestive heart failure 114 +/- 13%, control series 118 +/- 12%. The absence of a difference in PCr recovery rate and the greater PCr depletion by ischaemic work in patients with congestive heart failure suggest modifications that cannot be explained by a reduced blood flow to the muscle. 3. When comparing the two series, intracellular pH evolved similarly in normoxia and ischaemia during both work and recovery. Thus, no increase in anaerobic glycolytic activity appears when equivalent PCr depletion has occurred.

Topics: Adult; Aged; Exercise; Heart Failure; Humans; Hydrogen-Ion Concentration; Ischemia; Leg; Magnetic Resonance Spectroscopy; Male; Middle Aged; Muscles; Phosphocreatine

The renal handling of cyclosporine was studied in ischemically damaged kidneys in New Zealand White rabbits and nonischemic control animals. CsA, 25 mg/kg/day, was administered intravenously for 10 days starting with the day of operation. Blood CsA (B CsA) was higher in the ischemic group compared with the controls (median: 285 micrograms/L, range 95-785 micrograms/L vs. 170 micrograms/L, range 110-185 micrograms/L, P = 0.05) on day 1 after operation. B CsA dropped rapidly to a level equivalent to the controls by day 4 (median: 105 micrograms/L, range 60-280 micrograms/L vs. 195 micrograms/L, range 70-215 micrograms/L, P = NS). Median CsA clearance (C CsA) as a percentage of creatinine clearance (C Cr) was some ten-fold greater in the ischemic animals (6.32%, range 2.93-18.41% vs. 0.55%, range 0.13-0.78%, P less than 0.001) on day 1. The ratio gradually declined, approaching the value in controls by day 10 (0.86%, range 0.24-7.21% vs. 0.23%, range 0.16-0.73%, P = 0.05). The data suggest that renal impairment has an important effect on CsA blood levels. In the clinical situation this may be of particular importance during both oliguria and the recovery from acute tubular necrosis.

Topics: Animals; Creatinine; Cyclosporins; Ischemia; Kidney; Metabolic Clearance Rate; Phosphocreatine; Rabbits; Radioimmunoassay

Prolonged ischemia to skeletal muscle as occurs after an acute arterial occlusion results in alterations in adenine nucleotide metabolism. Adenosine triphosphate continues to be used for cellular functions, and an ischemia-induced degradation of phosphorylated adenine nucleotides is initiated. In this experiment we demonstrated the time-dependent aspect of adenine nucleotide depletion during ischemia and the production of large quantities of soluble precursors. In addition, we studied the rate of conversion of xanthine dehydrogenase to xanthine oxidase, a potential source of oxygen-free radicals, after controlled periods of total normothermic ischemia (4 hours and 5 hours) and during the reperfusion phase. During ischemia complete depletion of creatine phosphate occurred in both groups, and adenosine triphosphate fell from 22.1 +/- 1.3 to 10.3 +/- 1.4 mumol/gm dry weight after 4 hours and from 21.6 +/- 0.7 to 3.9 +/- 0.8 mumol/gm dry weight after 5 hours (p less than 0.05). During reperfusion, creatine phosphokinase resynthesis occurred in both groups, but adenosine triphosphate levels were not significantly increased (p greater than 0.05). A washout of lipid soluble products of adenine nucleotide metabolism occurred equally in both groups. The relationship between phosphorylated adenine nucleotides as measured by the energy charge potential fell significantly in both groups (p less than 0.05), but after the shorter period of ischemia (4 hours it returned to normal during early reperfusion but did not after 5 hours of ischemia. There was 21% +/- 4% necrosis after 4 hours and 51% +/- 8% after 5 hours of ischemic stress when assessed at 48 hours. In conclusion, the degree of adenine nucleotide degeneration as determined primarily by the length of the ischemic period, may be the most important determinant of the ultimate extent of skeletal muscle ischemic necrosis that results from an acute interruption of circulation.

Topics: Adenine Nucleotides; Animals; Dogs; In Vitro Techniques; Ischemia; Muscles; Phosphocreatine; Purines; Xanthine Dehydrogenase; Xanthine Oxidase

Rat leg muscles, rendered ischaemic 1 hour previously by ligation of the femoral artery, were submitted to 20 minutes exercise by electrical stimulation of the sciatic nerve. 31P-NMR spectroscopy was used to monitor the changes in high-energy phosphate content of the muscles before, during, and after exercise. Fifteen of the 35 studied muscles evolved toward total necrosis, whereas the others showed signs of recovery over a 2-5-hour postexercise period. Those muscles which did not subsequently recover contained significantly more inorganic phosphate (Pi) at rest (before exercise) than those which recovered. It is suggested that under acute ischaemic conditions the Pi level at rest is correlated with the extent of blood flow restriction and can be used to predict the severity of the ischemia.

Topics: Animals; Femoral Artery; Ischemia; Leg; Ligation; Magnetic Resonance Spectroscopy; Phosphates; Phosphocreatine; Phosphotransferases; Rats; Rats, Inbred Strains

The revascularization of ischemic extremities by retrograde arterial perfusion has been reported in clinical and experimental studies. The effect of retrograde perfusion on hemodynamics and metabolism of skeletal muscle was investigated in 86 rabbits with various types of AV-fistulas. Since blood flow was markedly reduced, levels of energy phosphates (ATP, CP) stabilized on a lower level. In all groups, lactate raised significantly. Focal morphological lesions were seen in all groups in a various degree. A high incidence of thrombosis was found at dissection. Maintenance of blood flow and metabolism after retrograde perfusion seems to be possible on a low level.

Topics: Adenosine Triphosphate; Anastomosis, Surgical; Animals; Arteriovenous Shunt, Surgical; Energy Metabolism; Hindlimb; Ischemia; Lactates; Lactic Acid; Male; Microsurgery; Muscles; Phosphocreatine; Postoperative Complications; Rabbits; Regional Blood Flow

Within the framework of the multifactor programme of ischemic heart disease (IHD) prevention, among the male population aged 40 to 59 years, the total mortality rate is shown to increase with elevation of blood pressure caused not only by cardiovascular disease but by other disease as well. The incidence of myocardial infarction and cerebral stroke is also shown to increase. Active complex therapeutic and preventive measures among the persons with arterial hypertension (AH) detected during a mass examination, have led to reduction of the prognostic value of AH for the total mortality rate and that in cardiovascular disease, in IHD in particular. Persons under 50 years with concurrent AH and IHD were found to have more pronounced changes.

Topics: alpha-Tocopherol; Animals; Culture Media; Heart Arrest, Induced; In Vitro Techniques; Ischemia; Male; Myocardial Contraction; Myocardial Reperfusion; Myocardium; Phosphocreatine; Rats; Vitamin E

In adult rat gastrocnemius muscles, on reperfusion after 45 min of tourniquet ischaemia, protein synthetic rates were depressed by over half for 1 h compared to normal (12%/day), and were at least one-third below normal for up to 5 h afterwards. Ischaemia caused muscle concentrations of phosphocreatine to be depressed by 70%, and those of lactate to be elevated by 350%; the proportion of ribosomes as polyribosomes was decreased by half. Unlike the rates of protein synthesis, all of these variables returned to normal after 35 min of reperfusion. When 25% of the blood volume was removed (for 10-45 min), there were falls in the rate of gastrocnemius protein synthesis and in phosphocreatine concentration, and an increase in lactate concentration. On blood replacement, protein synthesis and metabolite concentrations returned to normal within 15 min. Polyribosome profiles were unaffected by blood loss or replacement. There were highly significant correlations between the rate of gastrocnemius protein synthesis and both phosphocreatine concentration and 1/(lactate concentration), during blood loss and replacement, i.e. during both the fall and rise in muscle energy status. We conclude that the effects of ischaemia and blood loss on protein synthesis are not equivalent.

Topics: Adenosine Triphosphate; Animals; Ischemia; Lactates; Muscle Proteins; Muscles; Phosphocreatine; Polyribosomes; Rats; Regional Blood Flow; Reperfusion

These experiments evaluated the leukocyte as a potential source of oxygen free radical (OFR) generation during reperfusion injury in post-ischemic skeletal muscle. The infrarenal aorta of heparinized Sprague-Dawley rats was clamped for 90 min, declamped, and reperfused for 60 min. Hindlimb muscle resting transmembrane potential difference (Em) and high-energy phosphate content were determined at base line, during ischemia, and on reperfusion. Four groups were studied: a control group, a second group receiving superoxide dismutase and catalase (SOD + CAT) on declamping, a third group receiving dimethylmyleran (DMM) 7 days before the experiment to obtain a selective leukopenia (white blood cells = 1,210 +/- 144/mm3, neutrophils = 1.2%), and a fourth group pretreated with allopurinol (ALLO). During the ischemic period, resting Em was significantly depolarized (-78.6 +/- 0.5 mV from -90.3 +/- 0.3; P less than 0.05) in the control group, whereas creatine phosphate (CP) was depleted and ATP maintained. Data collected during the ischemic phase of the three other groups were similar to the control group (P = NS). On reperfusion, persistent depolarization of resting Em was observed despite restoration of muscle CP content in the control and ALLO groups (-75.4 and -77.0 mV, respectively). In contrast, significant repolarization of resting Em was noted after reperfusion in the SOD + CAT and DMM groups (-86.5 and -88.6 mV, respectively). These data implicate leukocyte-generated OFR as mediators of reperfusion-associated cellular membrane injury in postischemic skeletal muscle.

Topics: Adenosine Triphosphate; Animals; Cardiac Output; Catalase; Female; Glucose-6-Phosphate; Glucosephosphates; Hematocrit; Ischemia; Lactates; Leukocyte Count; Leukocytes; Membrane Potentials; Muscles; Phosphocreatine; Rats; Rats, Inbred Strains; Reperfusion Injury; Superoxide Dismutase

A blood-perfused rabbit hindlimb preparation was exposed to total ischemia (n = 4) or to severe hypoxemia (n = 4) where arterial PO2 was 5 +/- 2 (SE) Torr. O2 consumption (VO2), O2 transport (TO2), venous PO2 (PVO2), venous lactate concentration, and venous glucose concentration were measured. The relative concentration of ATP, phosphocreatine (PCr), inorganic phosphate (Pi), and intracellular pH (pHi) were monitored with 31P magnetic resonance spectroscopy. PCr/Pi decreased with the onset of ischemia or hypoxemia. The preparation was reoxygenated and allowed to recover for 30 min once PCr/Pi was less than 1.0. The periods of hypoxemia and ischemia lasted 56.0 +/- 10.0 and 63.8 +/- 2.5 min, respectively (NS). During ischemia PCr decreased and Pi increased compared with control (P less than 0.05) but returned to control with reperfusion. With hypoxemia PCr also decreased and Pi increased with respect to control (P less than 0.01) but did not recover with reoxygenation. VO2 and PVO2 in both groups returned to control during recovery. ATP did not change with ischemia but decreased with hypoxemia (P less than 0.05). Venous lactate concentration did not change with ischemia but increased with hypoxemia (P less than 0.05) and continued to rise during recovery. During recovery pHi decreased in the hypoxemic group (P less than 0.05) but not in the ischemic group. These data show that, under the conditions tested, rabbit skeletal muscle does not resynthesize PCr after a severe hypoxemic episode. Furthermore it appears that VO2 and PVO2 fail to portray the true state of cellular bioenergetics after a severe hypotemic insult.

Topics: Adenosine Triphosphate; Animals; Blood Glucose; Blood Pressure; Energy Metabolism; Hydrogen-Ion Concentration; Hypoxia; Ischemia; Lactates; Lactic Acid; Muscles; Oxygen Consumption; Perfusion; Phosphates; Phosphocreatine; Rabbits

Of all tissues of the extremities, muscle is the least tolerant of ischemia. Hypothermia of tissue is considered beneficial for the maintenance of viability of muscle in amputated limbs before surgical replantation, but it has never been established that conventional cooling in an ice bath or its equivalent (temperature of tissue, approximately 1 degree Celsius) is the optimum level of hypothermia for minimizing metabolic derangement in ischemic muscle. In this study, we first defined the time course and level of metabolic derangement of muscle in twenty-eight ischemic hind limbs in cats at 22, 15, 10, 5, and 1 degree Celsius. The levels of adenosine triphosphate and phosphocreatine and the mean intracellular pH of the muscles in the lateral aspect of the thigh in each limb were monitored with phosphorus nuclear magnetic-resonance spectroscopy over time. The excised muscles from six freshly amputated legs of live humans were then similarly studied to determine whether muscles from cats and from humans exhibit comparable bioenergetic responses to hypothermic ischemia. A final series of ten ischemic hind limbs from cats was studied by nuclear magnetic resonance and muscle biopsy for direct biochemical assay of tissue energy metabolites to compare the metabolic benefits of two different methods of preserving limbs: continuous cooling in an ice bath, and a newly devised protocol for the rapid induction and maintenance of so-called intermediate (10 +/- 5 degrees Celsius) hypothermia of tissue. Ischemic skeletal muscle in cats exhibited a paradoxical metabolic response to extreme cold (1 degree Celsius). The rate of metabolic deterioration progressively declined with decreasing temperature of tissue to 10 degrees Celsius. However, at 5 degrees Celsius, no additional benefit was detected, and at 1 degree Celsius, there was a significant acceleration in the rates of degradation of adenosine triphosphate and phosphocreatine and in the production of lactate. The rate of degradation of adenosine triphosphate in human ischemic muscle was also faster at 1 degree Celsius than at 10 degrees Celsius. This paradoxical response is apparently due to a severe inhibition of the calcium pump of the sarcoplasmic reticulum of the muscle cell at temperatures of less than 5 degrees Celsius. The inhibition permits an efflux of calcium to the myofibrils, which stimulates both glycolysis and the degradation of adenosine triphosphate by myofibrillar adenosine triphosphatase.

Topics: Adenosine Triphosphate; Animals; Cats; Energy Metabolism; Humans; Hydrogen-Ion Concentration; Hypothermia, Induced; In Vitro Techniques; Ischemia; Magnetic Resonance Spectroscopy; Male; Muscles; Phosphates; Phosphocreatine; Preservation, Biological; Replantation

During the development of acute hepatic encephalopathy, induced by acute liver ischemia, changes in brain 31P NMR spectra and EEG spectra were studied over 8:45 h in eight rats. At the end of this period the brain amino acid concentrations were determined. The results were compared with the same measurements in four normal and three portacaval shunted rats. Signs of acute HE, as judged by the EEG left index, started 5 h after the induction of acute liver ischemia. No accompanying significant changes in the cortical relative phosphocreatine and ATP concentration and intracellular pH were observed. The cortical relative Pi concentration had only slightly increased at t = 8 h. The concentrations of almost all measured brain amino acids, especially glutamine had increased at t = 8:45 h. At t = 8 h, rats with very severe HE had a small, but significant decrease of brain ATP concentrations. Their brain amino acid concentrations were more disturbed than in rats with less severe HE. It is concluded that a change in the cortical cerebral energy rich phosphate concentration is not an important pathophysiological mechanism during the development of acute HE. The observed changes in brain amino acids concentrations could be either part of a multifactorial pathogenesis or could be epiphenomena.

Topics: Adenosine Triphosphate; Amino Acids; Ammonia; Animals; Cerebral Cortex; Electroencephalography; Hepatic Encephalopathy; Ischemia; Liver Circulation; Magnetic Resonance Spectroscopy; Male; Phosphates; Phosphocreatine; Phosphorus; Rats; Rats, Inbred Strains; Reference Values

We have employed concurrent 31P- and 23Na-nuclear magnetic resonance (NMR) spectroscopy in conjunction with the paramagnetic shift reagents dysprosium-chelated tripolyphosphate and triethylenetetramine-hexa-acetic acid to observe the intracellular sodium and phosphorus signals in rat leg muscle. With induced ischemia in the leg, we find slowly falling phosphorylation potential. At a critical value of, associated with energetic failure of the Na+-K+ antiport, the intracellular sodium signal begins to increase. We find the following critical values: log, 3.12 +/- 0.32; pH, 6.86 +/- 0.13; Na+ influx with and without ouabain, 5.1 +/- 4.3 and 4.0 +/- 1.3 mol.l-1.h-1, respectively.

Topics: Adenine Nucleotides; Animals; Ischemia; Kinetics; Magnetic Resonance Spectroscopy; Male; Muscles; NAD; Phosphates; Phosphocreatine; Rats; Rats, Inbred Strains; Reference Values; Sodium; Thermodynamics

Forty-two patients (mean age 79 years) with acute ischaemia of one leg were evaluated in a prospective study. Forty-nine percent of the patients suffered from embolism, 29% from thrombosis while the etiology was uncertain in 22%. In 30 of the ischaemic legs and in 21 contralateral non-ischaemic legs the muscle energy metabolic status (ATP, ADP, AMP, ECP, PC, Cr and lactate) from the gastrocnemius muscle was measured and compared to values obtained from 24 healthy age-matched controls. There was a high degree of energy metabolic impairment in the ischaemic legs. Furthermore, the contralateral non-ischaemic legs were also energy depleted in comparison with those of the healthy controls. Legs with thrombosis were more energy-deprived than legs with embolism. Clinical evaluation of the degree of ischaemia and the level of occlusion correlated with energy metabolic parameters but the duration of ischaemia did not. The degree of metabolic impairment had no prognostic implication for the clinical outcome.

Topics: Adenine Nucleotides; Aged; Amputation, Surgical; Embolism; Energy Metabolism; Female; Humans; Ischemia; Lactates; Lactic Acid; Leg; Male; Muscles; Phosphocreatine; Prospective Studies; Thrombosis

Breast muscle of young chicks fed chow diets containing the creatine analog 1-carboxymethyl-2-iminoimidazolidine (cyclocreatine) accumulated up to 40 mumol/g wet weight of the synthetic phosphagen 1-carboxymethyl-2-imino-3-phosphonoimidazolidine (cyclocreatine-P2-). ATP levels were sustained at high values substantially longer in breast muscle of cyclocreatine-fed chicks, compared to control-fed chicks, during total ischemia initiated 2 h after injection of both groups with the beta-adrenergic agonist isoproterenol (5 mg/kg subcutaneous). For example, in chicks fed 0.5% cyclocreatine for 10-19 days ATP levels in isoproterenol-stimulated breast muscles after 1 h of ischemia at 37 degrees C were 6.1 mumol/g, compared to 1.9 mumol/g for the control-fed group, and after 2 h of ischemia were 3.5 mumol/g compared to 0.6 mumol/g for controls. Creatine-P reserves in isoproterenol-stimulated breast muscles of all dietary groups were essentially exhausted within the first hour of ischemia. In contrast, breast muscle of chicks fed either 1 or 0.5% cyclocreatine still contained 28 and 19 mumol/g of cyclocreatine-P, respectively, after 1 h of ischemia; after 2 h of ischemia, the respective cyclocreatine-P values were 20 and 13 mumol/g. Isoproterenol-stimulated chick breast muscle provides the first skeletal muscle model system for studying the molecular mechanisms by which dietary cyclocreatine helps sustain ATP levels during ischemia. Although adaptive factors are also involved, it is suggested that a significant portion of the ATP-sustaining activity of dietary cyclocreatine in ischemic breast muscle can be attributed to the unique thermodynamic properties of the accumulated cyclocreatine-P. These properties enable cyclocreatine-P to continue to thermodynamically buffer the adenylate system and transport high energy phosphate throughout the long muscle fibers at cytosolic pH values and phosphorylation potentials well below the range where the creatine-P system can function effectively. Synergism between glycolysis and this long-acting synthetic phosphagen might well help delay depletion of ATP levels in skeletal muscles during ischemia. Cyclocreatine feeding provides a unique experimental tool for quantitative evaluation of the proposed protective role of ATP against irreversible cellular damage in skeletal and cardiac muscles during ischemic episodes.

Topics: Adenosine Triphosphate; Animals; Chickens; Glycogen; Imidazolidines; Ischemia; Isoproterenol; Kinetics; Lactates; Male; Muscles; Phosphocreatine

It has been suggested that muscle ischemia could contribute to myositis ossificans and that the ischemia could result from prolonged retraction during surgery. Biopsy specimens of the gluteus medius muscle were taken at the beginning and the end of 30 primary total hip arthroplasties and the intracellular lactate and phosphocreatine (PCr) measured. Postoperative myositis ossificans was classified according to Brooker after 1 year, and the surface of the heterotopic bone projected above the greater trochanter in an anteroposterior roentgenogram was measured by planimetry. The findings suggest that muscle ischemia is not an important cause of myositis ossificans after hip arthroplasty, but elevated levels of lactate and lowered levels of intracellular PCr may occur as nonspecific responses to tissue trauma that through other mechanisms may lead to ossification.

Topics: Aged; Aged, 80 and over; Female; Hip Prosthesis; Humans; Ischemia; Lactates; Lactic Acid; Male; Middle Aged; Muscles; Myositis Ossificans; Osteoarthritis; Phosphocreatine; Postoperative Complications

Acute intestinal ischemia remains a catastrophic event even with the advent of modern diagnostic and vascular surgical techniques. An early noninvasive test would be valuable since early operation yields better survival rates. We have used an in vivo rat model to study acute intestinal ischemia after occlusion of the superior mesenteric artery (SMA). 31Phosphorus magnetic resonance spectroscopy (MRS), a noninvasive nondestructive technique, can detect the phosphorus metabolites most likely to be altered in ischemia: adenosine triphosphate, phosphocreatine (PCr), inorganic phosphate (Pi) and phosphomonoesters and phosphodiesters. Furthermore, intracellular pH can be estimated from the pH dependent position of the Pi spectral line relative to PCr. A tourniquet was loosely placed around the SMA in five Wistar rats through a transabdominal approach to the retroperitoneum. The abdomen was immediately closed. A 20 millimeter MRS surface coil was placed on the abdomen and 31Phosphorus spectra were accumulated. The SMA was then occluded and additional 31Phosphorus spectra were taken for the next 75 minutes. Significant (p less than 10(-4) changes in the position and magnitude of the spectra lines occurred within 20 minutes; the Pi position indicates severe intracellular acidosis and rapidly increases to three times its original magnitude. The PCr line decreases in magnitude. In a similar experiment, occlusion of the superior mesenteric vein (SMV) produced equivalent results. Occlusion of vessels other than the SMA or SMV not accompanied by transmural ischemia resulted in spectra unaltered from control. These findings support the application of phosphorus MRS to clinical studies.

Topics: Adenosine Triphosphate; Animals; Extracellular Space; Hydrogen-Ion Concentration; Ischemia; Magnetic Resonance Spectroscopy; Mesenteric Arteries; Mesenteric Vascular Occlusion; Phosphates; Phosphocreatine; Phosphorus; Rats; Rats, Inbred Strains; Renal Artery Obstruction

Rat kidneys were made ischemic for 5 to 120 seconds. Segments of individual nephrons were dissected from freeze dried sections and analyzed for ATP, phosphocreatine, glycogen, glucose, glucose-6-phosphate, lactate and creatine kinase. ATP fell most rapidly in proximal convoluted and straight tubules (PCT, PST) and distal convoluted tubules (DCT), and most slowly in glomerulus and papilla. Phosphocreatine levels ranged fivefold and was highest in DCT, where it approached that of brain. Creatine kinase ranged 100-fold with lowest level in PCT, where the ischemic fall in phosphocreatine was so slow as to suggest a function other than that of an energy reserve. Glycogen varied tenfold from modest levels in distal segments to very low levels in PST, and was not used rapidly in any segment. Glucose consumption and lactate production were most rapid in distal portions. High-energy phosphate consumption for the first 7.5 seconds of ischemia, calculated from these data, indicates roughly-equal energy metabolism in proximal and distal segments, with lower levels in papilla, and especially in glomerulus. The absolute values suggest that the in vivo metabolic rate of the nephron continued almost unabated for 5 or 10 seconds of ischemia.

Topics: Adenosine Triphosphate; Animals; Creatine Kinase; Energy Metabolism; Glucose; Glycogen; Ischemia; Kidney; Kidney Glomerulus; Kidney Medulla; Kidney Tubules; Kinetics; Lactates; Lactic Acid; Male; Nephrons; Phosphocreatine; Rats; Rats, Inbred Strains

In traumatic injuries to the extremities, with a circulatory insufficiency, the resultant ischemia leads to decreasing levels of the energy-rich compounds adenosine triphosphate (ATP) and phosphocreatine (PCr) and increasing levels of lactate in muscle. A tourniquet model for temporary ischemia was used to determine if hyperbaric oxygen treatment could enhance the cellular metabolic restitution when the circulation was restored. The circulation of the rat hindlimb was interrupted for 1.5 and 3 hours. After 1.5 hours of ischemia, the levels of adenosine triphosphate, phosphocreatine, and lactate were restored to normal in muscle biopsies taken 5 hours after the ischemia. After 3 hours of ischemia, there were marked reductions of adenosine triphosphate and phosphocreatine and elevated lactate values in the postischemic muscle, indicating severe ischemic damage. Hyperbaric oxygen treatment at 2.5 atm for 45 minutes reduced these changes significantly. A certain number of hyperbaric oxygen treatments were necessary to maintain this effect. It is concluded that repeated hyperbaric oxygen treatments in the postischemic phase stimulate aerobic metabolism.

Topics: Adenosine Triphosphate; Animals; Hindlimb; Hyperbaric Oxygenation; Ischemia; Lactates; Lactic Acid; Male; Muscles; Phosphocreatine; Rats; Rats, Inbred Strains; Regional Blood Flow; Time Factors; Tourniquets

Muscle biopsies were taken from 10 control subjects and five AMP deaminase (AMPD) deficient individuals before and after an ischaemic isometric exercise test and analysed for purine nucleotide, NAD+, creatine phosphate (CP) and lactate content. The decrease of ATP induced by the exercise test was significantly lower in the AMPD deficient patients than in the controls, but the decrease of creatine phosphate and the increase of lactate did not differ. There were no significant differences in the exertional performance level between patients and controls and no evidence was obtained of an increased energy expenditure per unit of performance in AMPD deficiency. The AMPD deficient individuals were equally capable of maintaining a high adenylate energy charge (EC) as the control subjects, which indicates a normal regulation of the balance between ATP consumption and ATP regeneration. ATP, ADP and total adenine nucleotide (TAN) but not AMP, were significantly elevated in the AMPD deficient patients as compared with the controls before as well as after the exercise test. This underlines the role of AMPD activity in the adenine nucleotide catabolism of skeletal muscle.

Topics: Adenosine Triphosphate; Adult; AMP Deaminase; Analysis of Variance; Female; Humans; Ischemia; Isometric Contraction; Lactates; Male; Middle Aged; Muscle Contraction; Muscles; Nucleotide Deaminases; Phosphocreatine; Purine Nucleotides

Isolated working hearts of 16 month old spontaneously hypertensive rats (SHR, n = 8) and age matched Wistar-Kyoto (WKY, n = 8) rats were exposed to 30 min global normothermic ischaemia followed by 60 min reperfusion. The hearts were routinely perfused at an afterload level of 13.3 kPa and a preload level of 1.0 kPa. The control values of left ventricular pressure, its maximal positive first derivative (dP1v/dtmax), coronary flow per gram heart tissue, and release of lactate and enzymes such as lactate dehydrogenase and aspartate aminotransferase were comparable in both groups. WKY rat hearts ejected almost twice as much perfusate per gram heart weight as the SHR hearts. In pressure-flow curves, obtained during the control period in SHR hearts, cardiac output was independent of changes in afterload, varying between 10.7 and 18.7 kPa. In contrast, in WKY rat hearts increases in afterload resulted in a progressive decrease in cardiac output. Reperfusion of the SHR hearts after 30 min of global normothermic ischaemia resulted in a poor recovery of cardiac output (13% of the control values) and dP1v/dtmax (32%) compared with the values in the WKY rat hearts (66% and 91% of the control values respectively). Reactive hyperaemia was prominent in the WKY rat hearts but completely absent in the SHR hearts. During one hour reperfusion, SHR hearts lost 3.5 times more lactate dehydrogenase and 2.5 times more aspartate aminotransferase than the WKY rat hearts. Pressure-flow curves, obtained during the reperfusion period, showed modest recovery of myocardial function of the WKY rat hearts at the lowest afterload level tested but completely depressed myocardial function of the SHR hearts at all afterload levels. Heart tissue contents of adenosine triphosphate and creatine phosphate after one hour of reperfusion were lower in the SHR than in the WKY rats, but compared with native values a comparable percentage decrease was seen in both groups of rats.

Topics: Adenosine Triphosphate; Animals; Aspartate Aminotransferases; Cardiac Output; Cardiomegaly; Coronary Vessels; Heart; Hypertension; Ischemia; L-Lactate Dehydrogenase; Myocardium; Perfusion; Phosphocreatine; Rats; Rats, Inbred SHR; Rats, Inbred WKY

Since fish hearts are resistant to the effects of hypoxia, comparison of the effects of hypoxia and ischaemia on fish and mammalian hearts may lead to better understanding of ischaemic injury in mammalian hearts. The ultrastructure and levels of ATP, creatine phosphate, and lactic acid were examined in hearts obtained from largemouth bass. Bass hearts were subjected to conditions of normoxia, ischaemia, hypoxia, and hypoxia in the presence of fluoride and cyanide. ATP levels remained stable during hypoxia and ischaemia, but fell during hypoxia in the presence of fluoride or fluoride plus cyanide. Changes in creatine phosphate and lactic acid indicated ATP was produced during hypoxia and ischaemia by glycolysis, by rephosphorylation from creatine phosphate, and by oxidative phosphorylation with oxygen obtained from myoglobin or the atmosphere. Ultrastructural changes were found similar to those reported in ischaemic mammalian heart, consisting of inter- and intracellular swelling, glycogen depletion, and mitochondrial alterations. Comparison of metabolic rates between fish and mammalian hearts suggests the lower rate in fish hearts may be the chief factor which permits stable ATP levels during hypoxia and ischaemia, and thus provides resistance to these conditions.

Topics: Adenosine Triphosphate; Animals; Fishes; Heart Ventricles; Humans; Hypoxia; Ischemia; Lactates; Lactic Acid; Microscopy, Electron; Myocardium; Phosphocreatine; Sodium Cyanide; Sodium Fluoride

Tumor tissue contains viable hypoxic regions that are radioresistant and often chemoresistant and may therefore be responsible for some treatment failures. A subject of general interest has been the development of non-invasive means of monitoring tissue oxygen. Pulse Fourier transform 31P NMR spectroscopy can be used to estimate intracellular nucleotide triphosphates (NTP), phosphocreatinine (PCr), inorganic phosphate (Pi) and pH. We have obtained 31P NMR spectra as an indirect estimate of tissue oxygen and metabolic status in a C3H mouse fibrosarcoma FSaII. Sequential spectra were studied during tumor growth in a cohort of animals and peak area ratios for several metabolites were computed digitally by computer. During growth, tumors showed a progressive loss of PCr with increasing Pi, and most tumors greater than 250 mm3 in volume had little or no measurable PCr. The smallest tumors (38 mm3 average volume) had PCr/Pi ratios of 1.03 +/- .24, whereas tumors 250 mm3 or more had an average PCr/Pi ratio of 0.15 +/- .04. Similarly derived NTP/Pi ratios decreased with tumor size, but this change was not significant (p = .17). Radiobiologic hypoxic cell fractions were estimated using the radiation dose required to control tumor in 50% of animals (TCD50) or by the lung colony technique. Tumors less than 100 mm3 had a hypoxic cell fraction of 4% (TCD50) while tumors 250 mm3 had a 40% hypoxic cell fraction (lung colony assay). These hypoxic fraction determinations correlated well with the depletion of PCr and decline in NTP/Pi ratios seen at 250 mm3 tumor volumes. Tumor spectral changes with acute ischemia were studied after ligation of the tumor bearing limb and were similar to changes seen with tumor growth. PCr was lost within 7 minutes, with concurrent increase in Pi and loss of NTP. Complete loss of all high energy phosphates occurred by 40 minutes of occlusion. In vivo tumor 31P NMR spectroscopy can be used to estimate tissue metabolic status and may be useful in non-invasive prediction of hypoxic cell fraction, reoxygenation, and radiation treatment response.

Topics: Animals; Energy Metabolism; Female; Fibrosarcoma; Hydrogen-Ion Concentration; Hypoxia; Ischemia; Magnetic Resonance Spectroscopy; Male; Mice; Mice, Inbred C3H; Nucleotides; Phosphates; Phosphocreatine; Sarcoma, Experimental

31P nuclear magnetic resonance (NMR) spectroscopy has been used to follow the metabolism of acutely ischemic rat small intestine and its recovery after reversal of ischemia. Loops of small intestine were subjected to occlusive external pressure for up to 60 minutes, followed by a recovery period. The depletion of PCr and ATP is rapid and complete within 20 minutes. Recovery from ischemia is also rapid but with recovery ATP levels lower than initial values after prolonged ischemic periods. Intestinal shock was avoided. Clinical recovery correlated with shorter ischemic periods. 31P NMR spectroscopy thus appears to be a suitable technique for studying the effects of pharmacological agents and other treatments for amelioration of ischemic effects on the bowel.

Topics: Adenine Nucleotides; Animals; Female; Intestines; Ischemia; Magnetic Resonance Spectroscopy; NAD; Phosphocreatine; Rats; Sugar Phosphates; Time Factors

In this study, the tolerance of skeletal muscle to tourniquet application (ischemia) and to acute compartment syndrome (ischemia and pressure) was compared. In five animals, the cuff of a pneumatic tourniquet was inflated to 350 millimeters of mercury at the level of the thigh for three hours. In five other animals, an acute experimental compartment syndrome was created in one anterolateral compartment by autologous plasma infusion. The compartment pressure (measured by wick catheter) was maintained at a level equal to the mean arterial pressure for three hours. At three hours, reperfusion was established in both groups, either by tourniquet release or by decompressive fasciotomy and epimysiotomy. During both the ischemic period and a two-hour recovery period immediately thereafter, the mean intracellular pH and high-energy phosphate profile (levels of adenosine triphosphate and phosphocreatine) of the muscles of the anterolateral compartment were monitored non-invasively by phosphorus nuclear magnetic-resonance spectroscopy. Muscle biopsies were done the following day to take specimens for electron microscopic analysis of ultrastructural cellular degeneration. During ischemia, the cellular levels of phosphocreatine decreased at an identical rate in both groups. In contrast, the levels of adenosine triphosphate diminished rapidly in the animals with the compartment syndrome, but remained unchanged in the tourniquet group. Ischemic muscle acidosis was more severe in dogs with the compartment syndrome. In the tourniquet group, the phosphocreatine, adenosine triphosphate, and pH were all normal within fifteen minutes after release of the tourniquet, but these values remained depressed even two hours after fasciotomy in the group with compartment syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adenosine Triphosphate; Animals; Biopsy; Compartment Syndromes; Dogs; Female; Hydrogen-Ion Concentration; Ischemia; Male; Microscopy, Electron; Muscles; Phosphocreatine; Pressure; Time Factors; Tourniquets

Caudal nerve conduction velocity and amplitude of nerve action potential increased progressively with age to 8 months after which time no further increases were demonstrated. Rat peripheral nerve was progressively more resistant to ischaemic-anoxic conduction failure with increasing age. This resistance to ischaemic conduction failure was paralleled by a progressive age-related decline in endoneurial O2 consumption. Endoneurial adenosine triphosphate and creatine phosphate values were also progressively reduced with age. 15 min of anoxia resulted in progressively smaller reductions in these nucleotide phosphates with increasing age to 8 months after which time little further change occurred. Nerve lactate response to anoxia was higher in young rats (1 and 2 months) than in older animals (8 and 21 months). High energy phosphate expenditure progressively declined with age to 8 months, then stabilized. These findings indicate that the major mechanism of resistance to ischaemic conduction failure is a progressive decline in energy requirements.

Topics: Action Potentials; Adenosine Triphosphate; Aging; Animals; Energy Metabolism; Ischemia; Lactates; Lactic Acid; Male; Neural Conduction; Oxygen; Oxygen Consumption; Peripheral Nerves; Phosphates; Phosphocreatine; Rats; Rats, Inbred Strains; Sciatic Nerve

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

The possible direct attenuating modification by diltiazem (DZ) 10(-6) M of ischaemia-induced metabolic damage was studied by 31P NMR spectroscopy (at 101.3 MHz) on retrogradely perfused rat hearts submitted to a 24 min, normothermic (37 degrees C), global low-flow ischaemia (1% of the pre-ischaemic spontaneous coronary flow), followed by a 30 min reperfusion. The presence of DZ 10(-6) M altered neither the heart rate and the left intraventricular pressure under normoxic conditions, nor the extent of ATP and CP depletion during ischaemia, whilst the intramyocardial Pi accumulation during ischaemia was significantly reduced (by about 30%). The intracellular acidification induced by ischaemia was initially less in the presence of DZ, but the pH values reached by the end of ischaemia were somewhat lower than in control (albeit not significantly so): 5.85 +/- 0.07 v. 6.00 +/- 0.07 (Means +/- S.E.M.). On reperfusion, DZ-treated hearts exhibited a greater oxidative phosphorylation capacity than did control hearts. Indeed, NMR spectroscopy revealed a prompter, greater and durable rephosphorylation of creatine together with a simultaneous more rapid and furthermore sharp drop in Pi content in DZ-treated hearts. Moreover, although NMR spectroscopy did not reveal any significant difference in ATP alteration on reperfusion in DZ-treated hearts as compared with controls, biochemical measurements indicated slightly higher ATP content at the end of reperfusion and, more particularly, a better recovery of the adenylate charge: 0.81 +/- 0.03 v. 0.72 +/- 0.03, means +/- S.E.M. (Pre-ischaemic value 0.90-0.91). The intracellular pH differed insignificantly from its pre-ischaemic value at the end of reperfusion in DZ-treated hearts (7.08), while remaining below initial values in controls (7.00). From these results, it is inferred that, at relatively low concentration (10(-6) M), DZ exerts a direct beneficial effect on the energy metabolism of the ischaemic heart without preserving high-energy phosphate compounds during ischaemia and, most importantly, without reducing the extent of the concomitant intracellular acidification.

Topics: Adenosine Triphosphate; Animals; Diltiazem; Energy Metabolism; Heart; Heart Rate; Hydrogen-Ion Concentration; Ischemia; Magnetic Resonance Spectroscopy; Male; Myocardium; Oxidative Phosphorylation; Phosphocreatine; Phosphorus Radioisotopes; Rats; Rats, Inbred Strains; Stroke Volume

To evaluate the temporal relationship and potential correlation between intramuscular phosphagen levels, lipid oxidation, and extent of muscle injury, a canine gracilis muscle model was used to study the consequences of a global ischemic episode for up to 7 h duration with reperfusion for 4 h. In this model the contralateral gracilis muscle was prepared identically to the test side but was not subjected to ischemia and thus served as a control. Blood flow, oxygen consumption, and lactate and glycerol release were measured before and after 2- and 7-h ischemic stress periods. The intramuscular metabolites, glycogen, lactate, phosphocreatine, and ATP, as well as free fatty acid conjugated dienes, were measured before, during, and after the ischemic insult. A 2-h ischemic insult resulted in minimal ultrastructural damage and complete regeneration of intramuscular phosphagens and glycogen on reperfusion with complete normalization of lipid oxidation products. In contrast, a 7-h ischemic insult resulted in profound injury at the ultrastructural level with an inability to restore intramuscular phosphagens and glycogen on reperfusion. This severe muscle injury correlated with a 2.5-fold increase in lipid oxidation products (free fatty acid conjugated dienes) and a decline in ATP levels below 5 mumol/g dry wt on reperfusion. Our results emphasize the prolonged glycolytic activity of skeletal muscle during global ischemia and document the increased production of oxygen free radical-mediated lipid oxidation products in irreversibly injured muscle.

Topics: Adenosine Triphosphate; Animals; Dogs; Fatty Acids, Nonesterified; Glycogen; Ischemia; Lactates; Lactic Acid; Lipid Peroxides; Microscopy, Electron; Muscles; Oxygen Consumption; Phosphocreatine; Regional Blood Flow; Time Factors

The effect of energy substrate depletion and of high lactic acid (LA) load on the development of irreversible cell injury was evaluated in the lateral gastrocnemius muscle of rabbits subjected to 4 hr of tourniquet hindlimb ischemia. Three groups of animals were studied. Group I, high ATP-ischemia, these animals were subjected to 4 hr of ischemia; group II, low ATP--low LA ischemia, in this group the gastrocnemius muscle was electrically stimulated for 5 min during ischemic conditions to reduce the glycogen store, a short reperfusion period was allowed after the stimulation in order to wash out the built up LA, and the muscle was then subjected to 4 hr of ischemia; group III, low ATP--high LA ischemia, in this group glycogen was depleted as in group II, but no reperfusion period was allowed before the 4 hr period of ischemia. In group I, ATP levels were well preserved during the ischemic period, whereas in the substrate-deprived groups (II and III) a rapid depletion of ATP and phosphocreatine (CP) occurred. The LA was twice as high in the "high LA" group (III) as in the "low LA" group (II) during the ischemic period. The extent of injury was evaluated after 24 hr of reperfusion by measuring ATP and CP content, and contractile force and by light microscopy. No or minor cell damage was found in group I. In group III--high LA--no recovery was obtained in any of the variables used for evaluation. In group II--Low LA--there was a certain recovery. ATP and CP increased to about 35% and contractile force to 25% of control. Morphologically about 20% of the muscle cells appeared to be unaffected by the ischemic insult. It is concluded that reduction of the glycogen available for ATP resynthesis during the ischemic period drastically reduces the ability of skeletal muscle to withstand prolonged ischemia. A high LA load seems to amplify the deleterious effects of a low initial substrate level.

Topics: Adenosine Triphosphate; Animals; Electric Stimulation; Glycogen; Ischemia; Lactates; Lactic Acid; Male; Muscle Contraction; Muscles; Phosphocreatine; Rabbits; Time Factors

We examined the effect of ischemia on nerve conduction in experimental diabetic neuropathy (EDN) and related electrophysiological changes to nerve adenosine triphosphate (ATP), creatine phosphate (CP), and lactate under anoxic conditions. Rats rendered diabetic with streptozotocin had a resistance to ischemic conduction block (RICB). Caudal nerve action potential (NAP) was well maintained for 10 min in controls and for 15 min in EDN, after which time NAP declined in both groups but more rapidly in normal rats. Time to 50% reduction in nerve ATP and CP was 10 and 3 min, respectively, in controls and delayed to 20 and 8 min in EDN. Rate of utilization of high-energy phosphate (approximately P) was linear for 5 min in controls to be followed by a progressive decline. In EDN rate of utilization of approximately P was linear to 15 min to be followed by a more gradual decline than in normal nerves. These findings suggest that the maintenance of nerve transmission in anoxic-ischemic states depends on anaerobic metabolism and that RICB in EDN is due in part to the ability of diabetic nerves to maintain a higher level of anaerobic glycolysis and for a longer time than normal nerves.

Topics: Action Potentials; Adenosine Triphosphate; Animals; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Energy Metabolism; Glycolysis; Ischemia; Lactates; Lactic Acid; Male; Nerve Block; Neural Conduction; Peripheral Nerves; Phosphocreatine; Rats; Rats, Inbred Strains; Time Factors

In addition to the determination of the presenting symptom of patients with peripheral vascular occlusive disease, evaluation of these patients may include the noninvasive measurements of ankle/arm pressure ratio, limb blood flow, and treadmill testing to evaluate the severity of the reduction in blood flow. We have included metabolic studies to assess the effect of this reduced blood flow in patients with stable intermittent claudication (n = 20), and with end-stage ischemia (night and rest pain) (n = 11), and in a control group without vascular disease (n = 8). No correlations were found between the resting limb blood flow, ankle/arm pressure ratios, maximum walking distance, and stated walking distance for the patients with stable claudication. Although the oxygen consumption was reduced only in the patients with end-stage ischemia, the percent oxygen extraction was increased to the same level in the patients with stable claudication and those with end-stage ischemia. Intramuscular stores of high-energy phosphates and glycogen were maintained in all groups with the lactate/pyruvate ratio increased only in the patients with end-stage ischemia. The complex interrelationships between the rate and distribution of blood flow with exercise and enzyme adaptation in patients with vascular disease make current resting hemodynamic and metabolic evaluations a poor reflection of the severity of the clinical condition within each patient group. Therefore laboratory testing may offer no advantage over clinical presentation in the overall evaluation of these patients.

Topics: Adenosine Triphosphate; Adult; Aged; Blood Pressure; Glycogen; Humans; Intermittent Claudication; Ischemia; Lactates; Lactic Acid; Leg; Middle Aged; Muscles; Oxygen Consumption; Phosphocreatine; Pyruvates; Pyruvic Acid; Regional Blood Flow

A simultaneous comparison of the effect of partial and total ischemia on skeletal muscle was made in dogs. The totally ischemic muscle had larger changes in adenosine triphosphate (ATP), creatine phosphate (CP), and cellular transmembrane potential difference (PD) during the 3-hour ischemic period than the partially ischemic muscle. Following recovery, all measured parameters in the totally ischemic muscle returned to normal, but paradoxically the PD in the partially ischemic muscle remained depressed despite the return to normal levels of ATP and CP. Contrary to the results in partially and totally ischemic brain tissue there was no evidence for higher levels of lactic acid in the partially ischemic muscle that could explain the persistent alteration in muscle cell function.

Topics: Adenosine Triphosphate; Animals; Dogs; Female; Ischemia; Lactates; Lactic Acid; Membrane Potentials; Muscles; Phosphocreatine

Following traumatic limb amputation it is common clinical practice to maintain the ischemic tissues in a hypothermic state until surgical reimplantation. Of all extremity tissues, muscle is the most sensitive to ischemia; it is therefore imperative that reperfusion be established before diffuse muscle necrosis. Although it has been shown both clinically and experimentally that hypothermia prolongs the viability of ischemic skeletal muscle, the presumed mechanism by which this occurs has not been confirmed at the cellular level. This study was undertaken to quantify the effect of conventional iced-saline hypothermia on anaerobic cell metabolism and high-energy phosphate depletion in traumatically devascularized muscle.. Phosphorus nuclear magnetic resonance spectroscopy (31P NMR) was employed to noninvasively monitor cellular phosphocreatine (PCr), ATP, and intracellular pH over time in ischemic cat hindlimb muscle under room temperature (22 degrees C) and 1 degree C hypothermic conditions.. Muscular PCr depletion was significantly retarded by tissue hypothermia but the rate of ATP depletion was not. A progressive, severe cellular acidosis was observed in the room-temperature muscle. Iced tissue cooling produced a dramatic initial rise in cell pH which significantly reduced the absolute degree of subsequent acidotic changes.. These findings question our understanding of hypothermic tissue preservation, which has generally been assumed to work on the basis of decreased tissue metabolism, thus conserving critical cellular ATP levels. The empirical benefit derived by cooling muscle in an iced medium may actually be related to the cellular alkalinization produced by tissue cooling, as this significantly mitigates the profound acidosis that would otherwise occur.

Topics: Adenosine Triphosphate; Amputation, Surgical; Amputation, Traumatic; Animals; Cats; Energy Metabolism; Hindlimb; Hydrogen-Ion Concentration; Hypothermia, Induced; Ischemia; Magnetic Resonance Spectroscopy; Male; Muscles; Phosphocreatine

Following distal arterial and venous cannulations in both hind limbs of 10 dogs, left leg arterial pressure was reduced to less than 50 torr (group I) and 50 to 75 torr (group II). Muscle membrane potential difference (PD) measurements, muscle biopsies, and arterial and venous blood samples were taken at baseline, after 3 hours of ischemia, and following 3 hours of reperfusion. Blood gas tensions and blood and muscle metabolites were measured. Muscle creatine phosphate levels fell during the ischemic period, but the adenosine triphosphate concentration remained normal. The PD fell in both groups during ischemia and declined further after reperfusion (p greater than 0.01). The deterioration in cell membrane function occurred in spite of intracellular energy repletion and persisted after reperfusion. The PD appears to be a more sensitive indicator of ischemia-induced cell dysfunction than levels of blood or intracellular metabolites. The cause of the progressive fall in the membrane potential is uncertain, but it may be due to cytotoxicity produced by oxygen free radicals.

Topics: Adenosine Triphosphate; Animals; Biopsy; Blood Pressure; Dogs; Energy Metabolism; Glucosephosphates; Ischemia; Lactates; Leg; Membrane Potentials; Muscles; Perfusion; Phosphocreatine; Pyruvates; Time Factors

A model of tourniquet ischaemia was developed in the hind limb of the rat, and the metabolic changes that occurred in the calf muscles were monitored by the non-invasive technique of phosphorus-31 nuclear magnetic resonance spectroscopy. During ischaemia the intramyocellular pH became acidic as the level of phosphocreatine declined and that of inorganic phosphate rose. Phosphocreatine was no longer detectable after approximately 2 hours and ATP was depleted after approximately 3.5 hours. Metabolic recovery was rapid (1 hour) if ATP was present when the tourniquet was released but was prolonged (3 or more hours) if ATP was depleted. Hourly release of the tourniquet for 10 minutes ensured the maintenance of ATP and rapid metabolic recovery. Release for intervals of only 5 minutes did not have the same protective effect and in fact worsened tissue pH during the period of tourniquet ischaemia. Heparin and corticosteroids were without effect during and after periods of tourniquet ischaemia.

Topics: Adenosine Triphosphate; Animals; Hindlimb; Hydrogen-Ion Concentration; Ischemia; Magnetic Resonance Spectroscopy; Male; Muscles; Phosphocreatine; Phosphorus; Rats; Rats, Inbred Strains; Spectrum Analysis; Time Factors; Tourniquets

Study of human tissues using 31P topical Magnetic Resonance is completely atraumatic; it allows simultaneous measurement of the concentrations of many important metabolites and of intracellular pH. In some critical situations, TMR yields more accurate results than those obtained by chemical analysis of tissue biopsies. We have shown that TMR can be calibrated to obtain quantitative measurements in human subjects. We have also shown that theories of control of glycolysis based on regulation by key metabolites of rate-limiting enzymes are inconsistent with the observed changes in intact muscle.

Topics: Adenosine Triphosphate; Creatine; Energy Metabolism; Forearm; Glycolysis; Humans; Hydrogen-Ion Concentration; Ischemia; Kinetics; Magnetic Resonance Spectroscopy; Muscles; NAD; Phosphates; Phosphocreatine

Currently there are no techniques available for the intraoperative on-line assessment of the adequacy of myocardial preservation during cardiac operation. The efficacy of a new intramyocardial pH electrode in quantitating myocardial ischemic damage and monitoring myocardial preservation was investigated by correlating changes in intramyocardial pH with the time course of metabolic, histologic, and ultrastructural alterations during global ischemia. Seventeen open-chest dogs were placed on cardiopulmonary bypass and the aorta was cross-clamped for 2 hours. In Group I (n = 8), aortic cross-clamping was performed under normothermia. Group II (n = 9) received 4 degrees C potassium cardioplegia immediately after cross-clamping and consecutively every 30 minutes thereafter. Intramyocardial carbon dioxide tension (Pco2) and intramyocardial pH were measured continuously. Serial transmural biopsies were obtained before and at 5, 15, 30, 60, 90, and 120 minutes after cross-clamping for biochemical and structural analysis. During the period of cross-clamping, mean myocardial temperature was 33 degrees C in Group I and 19 degrees C in Group II. Intramyocardial pH at the end of 2 hours of anoxic arrest reached 5.39 +/- 0.08 in Group I and 6.49 +/- 0.13 in Group II (both values p less than 0.01 compared to prebypass values). Intramyocardial Pco2 rose from 41 +/- 4 to 234 +/- 13 mm Hg in Group I (p less than 0.001) and did not change in Group II. Tissue content of adenosine triphosphate (ATP) decreased by 51% in Group I and by 14% in Group II (p less than 0.01 compared to prebypass value). Tissue creatine phosphate was depleted in Group I and decreased by 48% in Group II. The degree of ischemic damage assessed by a mean ischemic score was 2.15 +/- 0.06 in Group I and 0.75 +/- 0.19 in Group II (p less than 0.001). Irreversible structural damage assessed by electron microscopy occurred in Group I 60 to 90 minutes after cross-clamping and was associated with an intramyocardial pH below 6.2. No such damage was observed in Group II. Therefore, intramyocardial pH is shown to be a reliable indicator of the severity of ischemic damage during anoxic arrest under normothermic conditions and of the adequacy of preservation under hypothermic conditions. Measurement of intramyocardial pH may provide a potentially useful tool for the intraoperative on-line monitoring of the adequacy of myocardial preservation in patients undergoing cardiac operation.

Topics: Adenosine Triphosphate; Animals; Carbon Dioxide; Dogs; Female; Heart Arrest, Induced; Hydrogen-Ion Concentration; Hypothermia; Ischemia; Male; Monitoring, Physiologic; Myocardium; Phosphocreatine; Time Factors

Incomplete ischaemia was caused by clamping the aorta during reconstructive vascular surgery. After restoration of the blood flow extensive metabolic and morphological changes in the muscle tissue were observed. The adenylate (ATP + ADP + AMP) and the creatine (PCr + Cr) pools declined 30-40% and the energy charge of the adenine nucleotides dropped significantly. The metabolic pool changes were closely related to the changes in the lactate/pyruvate ratios. Morphological signs of membrane disturbances, such as fibre oedema and swelling of mitochondria, were seen in many muscle fibres 30 min after declamping. 5 days postoperatively, a number of mitochondrial abnormalities were observed and fibre regeneration was seen in places. The relative number of Type 2 fibres and the width of the capillary lumen were both related to the decrease of the metabolic parameters. Thus, the metabolic state and the fine structure of the incompletely ischaemic muscle were closely related to each other. The amount of Type 2 fibres seemed to be of special importance for the patho-physiological events in intermittently ischaemic muscle fibres.

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Adult; Aged; Constriction; Female; Humans; Intermittent Claudication; Ischemia; Lactates; Lactic Acid; Leg; Male; Middle Aged; Mitochondria, Muscle; Muscles; Phosphocreatine; Pyruvates; Pyruvic Acid

The increased susceptibility of hearts with chronic left ventricular hypertrophy (CLVH) to damage during ischemia has been suggested but not documented. The purpose of this study was to isolate ischemic events in hearts with CLVH from reperfusion events. Using physiological and biochemical parameters, we compared the rate and extent of myocardial injury during ischemic contracture between eight canine hearts with CLVH induced by subcoronary valvular aortic stenosis and 14 normal canine hearts. Preischemic myocardial blood flow was determined by injection of tracer microspheres. During cardiopulmonary bypass, each heart was instrumented with a left ventricular balloon and made globally ischemic. At control, contracture initiation, and contracture completion left ventricular transmural biopsy specimens were assayed for subepicardial and subendocardial adenosine triphosphate (ATP) and creatine phosphate (CP). Mitochondrial respiratory control indices for NAD-linked and FAD-linked substrates were measured. Preischemic endocardial blood flow in hearts with CLVH was significantly lower than in normal hearts. At control, subendocardial ATP and CP and the respiratory control index for NAD-linked substrate were significantly lower in hearts with CLVH than in normal hearts. Hearts with CLVH reached contracture initiation significantly sooner than normal hearts. All hearts demonstrated significant decreases in high-energy phosphate content and mitochondrial function during ischemia. Reperfusion injury notwithstanding, we concluded that hearts wih CLVH are more susceptible to ischemic injury than are normal hearts, perhaps related to lower endocardial blood flow, lower subendocardial high-energy phosphate stores, and depressed mitochondrial function prior to ischemia.

Topics: Adenosine Triphosphate; Animals; Aortic Valve Stenosis; Cardiomegaly; Coronary Circulation; Dogs; Ischemia; Mitochondria, Heart; Myocardial Contraction; Oxygen Consumption; Phosphocreatine

Topics: Adenosine Triphosphate; Animals; Brain; Glycogen Storage Disease Type V; Humans; Hydrogen-Ion Concentration; Ischemia; Magnetic Resonance Spectroscopy; Metabolism; Muscle Contraction; Muscles; Myocardium; Phosphates; Phosphocreatine; Phosphorus Isotopes

Five young males performed dynamic, submaximal contractions to exhaustion with the quadriceps muscle under arterial occlusion. The work load was 14.7 Watt (W). After 10 min rest with intact arterial circulation, the subjects commenced another bout to exhaustion; this process was repeated until a total of 10--16 bouts had been performed. Muscle biopsies were obtained immediately after the second, fifth, eighth, and last bout as well as 30 min after the last bout. The concentrations of adenosine triphosphate (ATP), creatine phosphate (CP), lactate, and glycogen were measured in each sample and some material underwent histochemical analysis. Muscle lactate was highest following the second work bout [22.9 mmol/kg wet weight (ww)] and gradually declined to 7.0 mmol/kg ww by the end of the last bout. CP level was low in all postexercise samples with the exception of a remarkably high CP (11.7 mmol/kg ww) after the last bout. Glycogen utilization tended to parallel muscle lactate levels, the rate of depletion being most rapid initially. Histochemical staining for glycogen depletion revealed that both type I and II fibres were low in glycogen, although type I was depleted most uniformly. In the first work bouts the high lactate and low CP levels in the total muscle could be responsible for the fatigue; none of these factors seem adequate to explain the development of the fatigue experienced in the later work bouts. It is concluded that muscle fatigue in this type of exercise is not related to substrate depletion or accumulation of metabolites, further that the fibre recruitment pattern is determined by the type and relative severity of performed work rather than local metabolic factors.

Topics: Adenosine Triphosphate; Adult; Glycogen; Humans; Ischemia; Lactates; Male; Muscles; Phosphocreatine; Physical Exertion; Time Factors

Muscle biopsies form the vastus lateralis muscle of the thigh were obtained from 11 patients before and at 15-min intervals following tourniquet application and 15 min after tourniquet release. The total circulatory occlusion time varied from 60 to 120 min. The concentrations of lactate, creatine phosphate and adenosine triphosphate were determined, and the muscle temperature was recorded. During the ischemic period, the lactate concentration increased from 1.9 mmol x kg-1 wet wt to 14.9 mmol x kg-1 wet wt after 90 min of ischemia. During the last 30 min of ischemia, no further increase in lactate concentration was observed. The creatine phosphate concentration decreased from 20.4 to 5.2 mmol x kg-1 wt wt after 120 min of ischemia. The temperature fell rapidly during the first 15 min from 35.9 degrees to 33.5 degrees and was then constant until 95 min when a further small decrease was observed. The adenosine triphosphate concentration did not change significantly during the ischemic period.

Topics: Adenosine Triphosphate; Adult; Biopsy; Body Temperature; Humans; Ischemia; Lactates; Leg; Muscles; Phosphocreatine; Time Factors; Tourniquets

The hemodynamic changes which occur when clamping and unclamping the aorta during reconstructive surgery might be a threat to the elderly patient with concomitant cardiac disease. In addition, the cross-clamping induces a temporary ischemia of the legs, with severe metabolic derangement after the release of the aortic clamp. We have studied the effect of a intraoperative adrenergic block (phenoxybenzamine plus metoprolol) on the central circulation and the skeletal metabolism in 14 patients undergoing aortic reconstruction to treat occlusive arteriosclerotic disease. Cardiac output, heart rate, arterial and pulmonary artery pressures, and cardiac filling pressures, as well as femoral venous blood flow were studied. Biopsy specimens of the lateral vastus muscle and blood samples from the radial artery and iliac vein were taken before aortic clamping, and before, 30 minutes, four and 16 hours after the aorta was unclamped, as well as five days postoperatively. In addition, intramuscular temperature and pH were measured. Glycogen, glucose, lactate, pyruvate, ATP, ADP, AMP, phosphocreatine (PCr) and creatine (Cr) contents of the muscle and lactate and pyruvate concentrations in iliac venous and radial arterial blood were determined using enzymatic fluorometric techniques. Mean arterial blood pressure (MAP) averaged 80 mmHg before clamping, chiefly because of the low systemic vascular resistance (SVR), and left ventricular stroke work (LVSW) was normal. At clamping MAP, SVR, LVSW, remained unchanged. MAP and LVSW were unaffected even though SVR decreased slightly after the aorta was unclamped and resulted in an increased cardiac output, mainly due to a higher stroke volume. No major change in the pulmonary circulation was observed. During clamping the muscle lactate/pyruvate ratio increased, intramuscular pH and femoral venous blood flow decreased indicating insufficient tissue perfusion. Energy charge (EC), the adenylate (ATP + ADP + AMP) and creatine (PCr + Cr) pools were, however, unchanged. In spite of a restored blood flow to the legs, a severe metabolic derangement of the muscle was observed after declamping, with lowered EC, ATP + ADP + AMP and PCr + Cr indicating cellular damage. No improvement in the condition of the cells was observed 16 hours after operation. In conclusion, we found that by using neurolept anesthesia and an intraoperative adrenergic block in combination with a differentiated fluid therapy the central circulation stabilized and was l

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Aorta; Arteriosclerosis; Constriction; Energy Metabolism; Glucose; Glycogen; Hemodynamics; Humans; Ischemia; Lactates; Muscles; Phosphocreatine; Pyruvates

Several metabolites and intracellular pH in intact organs can be studied in a non-destructive manner by phorphorus nuclear magnetic resonance (31P n.m.r.). This possibility was demonstrated by us nearly five years ago. Since then we have developed the appropriate physiological techniques and improved the n.m.r. method for the study of animal hearts and kidneys. Here we described measurements aimed at clarifying three problesm. (1) Having measured the enzyme-catalysed fluxes between phosphocreatine and ATP by the method of saturation transfer n.m.r., we examine the relations between energy supply and heart rate in the isolated perfused rat heart. (2) We describe experiments to establish the validity of the perfusion model. For the first time, we report 31P n.m.r. measurements of an in vivo rat heart and compare the results with those obtained for the perfused rat heart. (3) Ischaemia and metabolism in rabbit kidneys is investigated to establish the relation between functional and metabolic recovery after a renal transplant operation.

Topics: Adenine Nucleotides; Adenosine Triphosphate; Animals; Diphosphoglyceric Acids; Heart Rate; Ischemia; Kidney; Kidney Transplantation; Magnetic Resonance Spectroscopy; Myocardium; Perfusion; Phosphocreatine; Rats

The metabolic state of skeletal muscle and brain within intact rats is monitored using high resolution phosphorus nuclear magnetic resonance. Regional disturbances in metabolism (for example, localised ischaemia) are easily observed, indicating the diagnostic possibilities of the method. Measurements are made using 'surface' radiofrequency coils, which we discuss in detail.

Topics: Adenosine Triphosphate; Animals; Brain; Energy Metabolism; Hydrogen-Ion Concentration; Ischemia; Magnetic Resonance Spectroscopy; Models, Structural; Muscles; Phosphates; Phosphocreatine; Rats

Topics: Adenine Nucleotides; Animals; Creatine; Energy Metabolism; Epinephrine; Female; Glycogen; Imidazolidines; Ischemia; Kinetics; Mice; Muscles; Phosphates; Phosphocreatine; Rigor Mortis

Brief periods of ischemia have been shown to produce marked reactive hyperemia in both red (slow) and white (fast) skeletal muscle. However, evidence is lacking for specific vasodilator metabolites which are rapidly produced in ischemic skeletal muscle. The present study examined the effects of 1 and 3 minutes of ischemia on creatine phosphate (CrP), adenine nucleotide metabolism, and anaerobic glycolysis in red anterior (ALD) and white posterior latissimus dorsi (PLD) muscles of the chicken. Tissue metabolite concentrations were determined from perchloric acid or trichloroacetic acid extracts using enzymatic assay or high pressure liquid chromatography. CrP or adenine nucleotides were not significantly altered in either muscle following 1 or 3 minutes of ischemia. However, adenosine increased by 611% in the ALD at 1 minute. Following 3 minutes of ischemia, adenosine concentrations were elevated by 439% and 201% in the ALD and PLD, respectively. The PLD showed the greatest increases in inosine and IMP. Inorganic phosphate increased by 67% and lactate increased by 142% in the ALD at 3 minutes. The PLD, which is reported to have a high anaerobic glycolytic capacity, showed no increase in lactate. These results support the hypothesis that adenosine may be a mediator of akeletal muscle reactive hyperemia following short periods of ischemia.

Topics: Adenosine; Adenosine Triphosphate; Animals; Chickens; Glycolysis; Inosine; Ischemia; Male; Muscles; Phosphocreatine

In experiments with dogs, three different methods of inducing a reversible cardiac arrest were compared: (A) the ischemic arrest for 45 min, (B) the cardiac arrest for 90 min due to injection of Cardioplegin according to KIRSCH, and (C) the cardiac arrest for 90 min due to infusion of solution LK 352 according to BRETSCHNEIDER. The body temperature was reduced to 30 degrees C during the period of cardiac arrest. From the alterations in the adenylic acid system of the left ventricular myocardium at the end of the period of myocardial standstill and after 60 min of recovery, it can be deduced that the best myocardial protection is given by method C. Method A has the least effect.

Topics: Adenine Nucleotides; Adenosine Triphosphate; Animals; Aspartic Acid; Dogs; Drug Combinations; Glycogen; Heart; Heart Arrest, Induced; Ischemia; Lactates; Myocardium; Phosphocreatine; Procaine; Sorbitol

In order to investigate possible differences in the reaction to hypoxic conditions between "red" and "white" skeletal muscle, cats were subjected to a 2 h period of either hemorrhagic shock or hind limb tourniquet ischemia, and the hypoxia induced changes were studied in the soleus and lateral gastrocnemius muscles. Muscle biopsies were analysed for ATP, CP, glucose, G 6-P and lactate. Using microelectrodes, the resting membrane potential was repeatedly measured. Both experimental models resulted in increased tissue lactate levels and a successive decrease in the membrane potential of both muscles studied. No reduction of the high energy phosphagen content (ATP + CP) occurred in any of the muscles during shock. The tourniquet ischemia resulted in a 40% reduction of the ATP + CP content in the soleus muscle, whereas in the gastrocnemius muscle no significant reduction occurred. A significant correlation was found between the tissue lactate content and the membrane potential under both conditions and in both muscles studied. It is concluded that "red" muscles are more susceptible to metabolic derangement than "white" muscles during total ischemia, whereas during hypovolemia "red" muscles appear to be protected from early hypoxic damage, probably due to a redistribution of skeletal muscle blood flow.

Topics: Adenosine Triphosphate; Animals; Cats; Female; Glucose; Glucosephosphates; Ischemia; Lactates; Membrane Potentials; Muscles; Phosphocreatine; Shock, Hemorrhagic; Tourniquets

The relevance of two direct techniques for monitoring of cellular function during tissue hypoxia has been evaluated. Tissue pH and cellular transmembrane potentials were registered in canine skeletal muscle during intestinal exteriorization shock and during prolonged local tourniquet ischemia. The obtained pH and transmembrane potential changes were correlated to simultaneous changes in high-energy phosphagen (ATP + CP) and lactate levels in skeletal muscle. In control dogs no significant changes in either of the studied variables occurred. Intestinal exteriorization shock as well as local tourniquet ischemia resulted in a gradual increase in tissue lactate and a concomitant decrease in tissue pH and transmembrane potentials. In both experimental situations there was a close correlation between the transmembrane potential reduction and the tissue lactate increase. Tissue pH registrations, on the other hand, did not similarly reveal the full extent of the tissue lactate increase under the two experimental conditions. Possible reasons for this discrepancy are discussed. On the basis of the present results it may therefore be concluded that the transmembrane potential seems to be a better variable for revealing the full extent of cellular metabolic deterioration during various situations with tissue hypoxia.

Topics: Adenosine Triphosphate; Animals; Blood Pressure; Dogs; Electrophysiology; Hindlimb; Hydrogen-Ion Concentration; Ischemia; Lactates; Membrane Potentials; Muscles; Phosphocreatine; Shock

Axoplasmic transport of cat sciatic nerves was studied in vitro in a chamber in which maximal alpha action potentials could also be elicited. After initiation of N2 anoxia, electrical responses fell to zero at an average time of 22 min. A shorter time to zero of 11 min was seen during a second period of anoxia. A good recovery of both action potential responses and axoplasmic transport occurs after a period of anoxia lasting 1--1.5 hr. An apparent failure of recovery of axoplasmic transport was seen after 2 hr of anoxia with a good recovery of electrical responses. Axoplasmic transport tended to return toward normal when more time was allowed for recovery after anoxia. An adequate supply of approximately P was shown to be present by measurement of ATP and creatine phosphate levels. The delay in recovery of transport thus signifies a failure of utilization of approximately P by the transport mechanism. Longer periods of anoxia and recovery were limited in vitro and for this reason, ischemic anoxia was produced in vivo. Blood pressure cuffs were placed on the upper thigh of cats and maintained for times of 1--8 hr at pressures of 300-310 mm Hg. Then, recovery times up to 7 days were allowed. It was shown that axoplasmic transport could gradually recovery after an anoxia lasting up to 6-7 hr if sufficient recovery times were allowed. A possible explanation for the delay in the recovery of axoplasmic transport and the disassociation in the earlier recovery of electrical responses as against the recovery of transport was discussed.

Topics: Action Potentials; Adenosine Triphosphate; Animals; Axonal Transport; Cats; Energy Metabolism; Hypoxia; In Vitro Techniques; Ischemia; Nerve Tissue Proteins; Phosphocreatine; Sciatic Nerve

Topics: Adenosine Triphosphate; Animals; Brain; Cats; Female; Fluorescence; Freezing; Ischemia; Lactates; Male; Methods; NAD; Phosphocreatine

Topics: Adenosine Triphosphate; Animals; Brain; Brain Chemistry; Cats; Energy Metabolism; Female; Ischemia; Lactates; Male; Microcirculation; NAD; Phosphocreatine

The refinement of techniques for extremity surgery makes it urgent to get more information at cell level of the effects of tourniquet times exceeding the usually accepted 90--120 min. Therefore, in the present experiments, the cellular metabolic and functional restitution of canine skeletal muscle after 3 h of complete tourniquet ischemia was studied. During the ischemia and after recirculation, repeated skeletal muscle samples were taken for ATP, CP and lactate analyses. At the same time periods, blood from a regional vein and vena cava was drawn for pH, pyruvate and lactate analyses. Cellular function was evaluated from repeated measurements of transmembrane potentials. The tourniquet ischemia resulted in a rapid decrease of CP to 40% of the initial level within 1 h and a continuous decrease of ATP. The lactate levels increased continuously. The transmembrane potentials decreased from an initial level of --90 to --54 mV. The release of the tourniquet resulted in a hyperemic reaction and a rapid regain of tissue CP and ATP levels within 5 min of recirculation. There was a continuous washout of lactate up to about 1 h after the release and the transmembrane potentials were normalized after about the same time period. The latter parameters indicate that areas of no-reflow persisted for up to 1 h after restored circulation. The results indicate that after a 3-hour tourniquet ischema, the cellular energy metabolism as well as the membrane function are completely normalized after about 1 h of recirculation.

Topics: Adenosine Triphosphate; Animals; Dogs; Extremities; Ischemia; Lactates; Membrane Potentials; Muscles; Phosphocreatine; Tourniquets

The purpose of the reported experiments was to measure the strial concentrations of adenosine triphosphate (ATP), adenosine diphosphate (ADP), and adenosine monophosphate (AMP) in order to arrive at estimates of three commonly used adenylate ratios. Under normal conditions, the concentrations of ATP, ADP, and AMP were found to be 11.4, 3.7, and 0.6 mmoles/kg dry weight, respectively. Of the three substances, AMP is the most sensitive indicator of metabolic stress, since its concentration doubles within 6 sec. of ischemia and reaches a peak level of about 1500% of the control following 65 sec. of ischemia. Under normal conditions, the "adenylate energy charge," the "energy status," and the "phosphorylation state" amount to 0.84, 3.0, and 1.52 gram wet weight/mumole, respectively. In ischemia of 10 min. duration, the adenylate energy charge decreases 3 fold, the energy status 7 fold and the phosphorylation state 14 fold. The size of the adenylate pool shows a slight increase in the earliest stage of ischemia, but declines progressively thereafter. The apparent equilibrium constant of strial adenylate kinase was found to be 0.48. The advantages and limitations of the different adenylate ratios, as indicators of metabolic health and as regulatory parameters, are discussed.

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Adenylate Kinase; Animals; Cochlea; Energy Metabolism; Glycolysis; Guinea Pigs; In Vitro Techniques; Ischemia; Oxidative Phosphorylation; Phosphates; Phosphocreatine; Stria Vascularis

Topics: Adenosine Triphosphate; Adolescent; Animals; Aortic Coarctation; Child; Child, Preschool; Dogs; Energy Metabolism; Humans; Hydrogen-Ion Concentration; Hypotension, Controlled; Hypoxia; Ischemia; Lactates; Membrane Potentials; Muscles; Phosphocreatine; Pyruvates; Surgical Procedures, Operative; Tourniquets

Topics: Adenosine Triphosphate; Animals; Brain; Cerebral Cortex; Cyclic AMP; gamma-Aminobutyric Acid; Gerbillinae; Glucose; Glycogen; Ischemia; Lactates; Phosphocreatine; Recurrence

Topics: Adenine Nucleotides; Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Blood Glucose; Brain; Cyclic AMP; Cyclic GMP; Energy Metabolism; Gerbillinae; Glucose; Glycogen; Ischemia; Kinetics; Lactates; Phosphocreatine

A comparative investigation was made on muscle tissue of man, dog and rat during ischemia of five hours duration. The content of energy rich phosphates was measured. The ATP level decreased after two hours ischemia to 68% in man, to 45% in the dog, and to 23% in the rat. By five hours it had fallen further to 25% in man, 9% in the dog and only 1% in the rat. It is concluded that human muscle has a higher tolerance to ischemia.

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Creatine; Dogs; Energy Metabolism; Glycogen; Humans; Ischemia; Lactates; Muscles; Phosphocreatine; Rats; Time Factors

In 6 open chest dogs, regional myocardial function und metabolic changes (ATP, creatine phosphate, lactate) were studied during coronary flow reduction in LAD by ultrasonic dimension gauges and transmural biopsies. After reduction of the perfusion pressure from 108 to 50 mm Hg the ischemic segment showed a marked dyskinesis: the enddiastolic segment length increased by 7%, and segment shortening and segment stroke work decreased by 22% and 63% respectively. Left ventricular (LV) enddiastolic pressure rose from 5 to 8 mm Hg (p less than 0.05). Heart rate, LV systolic pressure, LV max dP/dt and Vpm did not change significantly.

Topics: Adenosine Triphosphate; Animals; Coronary Circulation; Dogs; Heart; Ischemia; Lactates; Myocardial Contraction; Myocardium; Partial Pressure; Phosphocreatine

Topics: Adenosine Triphosphate; Animals; Brain; Cyclic AMP; Gerbillinae; Glucose; Glucosephosphates; Glycogen; Ischemia; Lactates; Phosphocreatine; Uridine Diphosphate Glucose

Topics: Adenine Nucleotides; Animals; Brain; Creatine; Energy Metabolism; Glucose; Glycogen; Glycolysis; Hypoxia; Ischemia; Kinetics; Male; Mice; Phosphocreatine

Topics: Adenosine Triphosphate; Animals; Aorta, Thoracic; Blood Flow Velocity; Coronary Artery Bypass; Coronary Vessels; Heart Arrest, Induced; Humans; Hypothermia, Induced; In Vitro Techniques; Ischemia; Male; Myocardium; Organ Preservation; Perfusion; Phosphocreatine; Rats; Tissue Preservation

Topics: Adenosine Triphosphate; Animals; Cerebral Cortex; Citrates; Cyclic GMP; Dopamine; Energy Metabolism; gamma-Aminobutyric Acid; Gerbillinae; Glutamates; Ischemia; Neurotransmitter Agents; Norepinephrine; Nucleotides; Phosphocreatine; Serotonin

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Cerebral Cortex; Energy Metabolism; Freezing; Gerbillinae; Ischemia; Lactates; Male; Nitrogen; Organophosphorus Compounds; Phosphocreatine; Postmortem Changes; Temperature; Time Factors

The extent of cellular metabolic deterioration and its reversibility was studied on human skeletal muscle needle biopsies during operations in bloodless field. The tissue levels of high energy phosphates and glycolytic metabolites were analyzed after various times of tourniquet ischemia and compared to contralateral control extremity levels. In the ischemic extremity the phosphocreatine (CrP) levels decreased by 40% within 30-60 min and after 60-90 min a 60% reduction was found. No significant ATP changes occurred. Lactate levels increased by 225% after 30-60 min and by 300% after 60-90 min. The glucose and G-6-P levels increased slightly and indicated glycogenolysis. The rate of the metabolic changes decreased with ischemia time. In the control leg no significant metabolic changes could be seen. After the release of the tourniquet there was a rapid restoration of the phosphagen content and clearance of lactate in the ischemic leg. Near control levels of these substances were seen already after 5 min. The present results show that clinical tourniquet ischemia of up to 90 min duration produces less pronounced metabolic alterations than those seen in working muscle.

Topics: Adenosine Triphosphate; Adolescent; Biopsy, Needle; Child; Child, Preschool; Energy Metabolism; Glucose; Glucosephosphate Dehydrogenase; Humans; Ischemia; Lactates; Leg; Muscles; Phosphocreatine; Time Factors; Tourniquets

The authors studied the effect on cortical metabolites of intracranial hypertension produced by the infusion of mock cerebrospinal fluid into the cisterna magna in rabbits subjected to 15 minutes of cerebral oligemia (20 torr) or 15 minutes of complete ischemia. In both groups high-energy metabolites were exhausted within the first 5 minutes of the 15-minute insult. Significant recovery of the high-energy intermediates occurred within 15 minutes of reperfusion, well before return of electroencephalogram (EEG) activity. Continued reperfusion, during which electrical activity and function were returning, brought only moderate improvement in energy metabolites. In contrast, severe lactic acidosis persisted at least 15 minutes after insult, but was reduced by the time EEG activity returned. At no time were there striking differences in metabolites between the oligemic and ischemic groups. These results indicate that recovery in general, and the significantly earlier recovery of oligemic as compared to ischemic animals, cannot be explained on the basis of energy supply. Whether the persistence of lactic acidosis is an important factor limiting return of function requires further study.

Topics: Adenosine Triphosphate; Animals; Brain; Electroencephalography; Energy Metabolism; Glutamates; Intracranial Pressure; Ischemia; Lactates; Phosphocreatine; Rabbits; Time Factors

Hemodynamic and metabolic characteristics of an isolated guinea pig heart preparation perfused with a pyruvate fortified Krebs-Ringer-bicarbonate solution are described. The preparation is stable for more than 90 min with respect to coronary flow, heart rate, left ventricular pressure, dP/dt, oxygen consumption, and myocardial high energy phosphate levels. The changes in coronary flow induced by alterations of perfusion pressure, ischemia, and hypoxia resemble those seen under in vivo conditions. The preparation also exhibits concentration dependent and reproducible changes in coronary resistance upon administration of adenosine and papaverine. The in vivo like features of this preparation can be mainly attributed to the use of pyruvate as additional and preferentially utilized substrate. The preparation appears to be suitable for quantitative studies of myocardial metabolism and heart function as well as for investigations of the coronary system.

Topics: Adenine Nucleotides; Adenosine; Animals; Blood Flow Velocity; Blood Pressure; Coronary Vessels; Female; Glucose; Guinea Pigs; Heart; Heart Rate; Hemodynamics; Hypoxia; In Vitro Techniques; Ischemia; Male; Myocardium; Organ Size; Oxygen; Oxygen Consumption; Papaverine; Partial Pressure; Perfusion; Phosphates; Phosphocreatine; Pyruvates; Regional Blood Flow; Solutions; Vascular Resistance

The metabolic states of various tissues of newborn rabbits were studied before and after periods of ischemia of 5-40 min. The contents of substances of the energy distributing adenylic acid-creatine phosphate system as well as glycogen, glucose and lactate were determined and the results are discussed in comparison with the well-known values from ischemic tissues of adult rabbits. The preservation of high energy phosphates as well as the rate of glycolytic energy production during the course of ischemia was quite identical in the myocardium of newborns and adults in contrast to the different ability of newborn and adult rabbits to maintain circulation in anaerobic conditions. In the central nervous system the ATP contents decreased to very low levels within a few minutes in both groups although the glycolytic energy production was rather different. But the larger amounts of adenine nucleotides present in the newborns at any time of ischemia indicate a better chance of postischemic recovery. In the livers and the kidneys of the newborns higher rates of glycolytic energy production led to better preservation of the energy-rich substances while in skeletal muscle and the lung only slight differences occurred between newborns and adults.

Topics: Adenine Nucleotides; Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Animals, Newborn; Bone and Bones; Brain; Energy Metabolism; Glucose; Glycogen; Ischemia; Kidney; Lactates; Liver; Myocardium; Phosphocreatine; Rabbits

Topics: Adenosine Triphosphate; Animals; Cardiac Surgical Procedures; Extracorporeal Circulation; Heart; Heart Arrest, Induced; Hyperkalemia; Hypothermia; Ischemia; Male; Myocardium; Perfusion; Phosphocreatine; Potassium; Rats; Ventricular Fibrillation

Topics: Adenosine Triphosphate; Arteries; Cardiac Surgical Procedures; Citrates; Coronary Vessels; Heart; Heart Arrest, Induced; Humans; Injections, Intra-Arterial; Ischemia; Myocardium; Perfusion; Phosphocreatine; Potassium; Ventricular Fibrillation

Topics: Adenosine Triphosphate; Amines; Animals; Brain; Brain Chemistry; Cerebellum; Energy Metabolism; Fructosephosphates; Gluconates; Glucose; Glucosephosphates; Glycogen; Hypoxia, Brain; Ischemia; Isocitrates; Lactates; Malates; Mice; NAD; NADP; Niacinamide; Phosphocreatine; Ribose

Topics: Adenosine Triphosphate; Animals; Biopsy; Cardiac Surgical Procedures; Dogs; Extracorporeal Circulation; Hypothermia, Induced; Ischemia; Microscopy, Electron; Myocardial Infarction; Myocardium; Phosphocreatine; Potassium; Sodium

Acute gastric erosions following hemorrhagic shock (stress ulceration) have been attributed to gastric hyperacidity, altered gastric secretion of mucus and an abnormal permeability of the gastric mucosa to H(+). This report aims at presenting evidence supporting an alternate hypothesis: the event linking shock-induced gastric mucosal ischemia to mucosal necrosis is a deficit in gastric mucosal energy metabolism. Our experimental procedure consisted of harvesting the stomachs of rats and rabbits by "stop-freeze" (liquid N(2)) at different intervals after the induction of hemorrhagic shock. Levels of adenosine-phosphates and of glycolytic intermediates in gastric mucosa were measured. We studied the changes in the levels of these substrates produced by shock as well as by factors capable, when combined with shock, of rendering the gastric mucosa more vulnerable to stress ulceration. The influence of shock and of these modifying factors were evaluated by comparison with data from appropriately designed control experiments. In parallel experiments we examined the frequency of stress ulceration (gross and microscopic) under these same standard conditions. There have emerged from these studies a number of observations all based upon data with the highest statistical significance. The data are consonant with the hypothesis stated above: an energy deficit severe enough to cause cellular necrosis is the event linking shock-induced gastric mucosal ischemia and stress ulceration.

Topics: Adenine Nucleotides; Adenosine Triphosphatases; Animals; Energy Metabolism; Fasting; Gastric Mucosa; Glucosephosphates; Glycogen; Ischemia; Lactates; Liver; Male; Muscles; Peptic Ulcer; Phosphocreatine; Pyruvates; Rabbits; Rats; Shock, Hemorrhagic; Taurocholic Acid

Topics: Adenosine Triphosphate; Animals; Brain Death; Cerebrovascular Disorders; Electrophysiology; Glucose; Guinea Pigs; Ischemia; Lactates; Limbic System; Phosphocreatine; Synaptic Transmission; Time Factors

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Blood Circulation Time; Blood Pressure; Brain; Brain Chemistry; Brain Injuries; Brain Stem; Carotid Arteries; Cerebral Angiography; Cerebral Cortex; Cerebrovascular Circulation; Energy Metabolism; Heart Rate; Ischemia; Male; Phosphocreatine; Pulse; Rats; Subarachnoid Hemorrhage

Topics: Acidosis; Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Anemia; Animals; Asphyxia; Brain; Brain Diseases; Carbon Dioxide; Dogs; Energy Metabolism; Glucose; Hemoglobins; Humans; Hypoxia; Ischemia; Ischemic Attack, Transient; Lactates; Oxygen; Oxygen Consumption; Partial Pressure; Phosphocreatine; Rats; Time Factors

Topics: Acidosis; Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Blood Glucose; Blood Pressure; Body Temperature; Brain; Creatine; Energy Metabolism; Glucosephosphates; Glycogen; Hydrogen-Ion Concentration; Hyperglycemia; Hypoglycemia; Ischemia; Lactates; Phosphocreatine; Pyruvates; Rats

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Blood Glucose; Blood Pressure; Creatine; Glycogen; Hindlimb; Ischemia; Lactates; Male; Muscles; Necrosis; Phosphocreatine; Rats; Time Factors; Tourniquets

Topics: Adenine Nucleotides; Adenosine Triphosphate; Animals; Biological Transport; Blood Circulation; Blood Pressure; Carbohydrate Metabolism; Cell Membrane Permeability; Coronary Vessels; Glucose; Glucosephosphates; Glycogen; Glycolysis; Hypoxia; Insulin; Ischemia; Lactates; Myocardium; Perfusion; Phosphocreatine; Pyruvates; Rats

Topics: Adenosine Triphosphate; Animals; Asphyxia; Brain; Cochlea; Ear; Ear, Inner; Energy Metabolism; Ethacrynic Acid; Ischemia; Labyrinthine Fluids; Metabolic Clearance Rate; Organ of Corti; Phosphates; Phosphocreatine

Topics: Adenosine Triphosphate; Animals; Ischemia; Muscle Contraction; Muscles; Phosphocreatine; Swine

Topics: Adenine Nucleotides; Adenosine Triphosphate; Animals; Blood Glucose; Brain; Carbon Isotopes; Chickens; Citrates; Cyclic AMP; Dietary Carbohydrates; Fructosephosphates; Galactose; Glucose; Glucosephosphates; Glycerophosphates; Glycogen; Glycolysis; Hypoxia; Ischemia; Kinetics; Lactates; Male; Neurons; Phosphocreatine; Tritium

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: Adenosine Diphosphate; Adenosine Triphosphate; Animals; Brain; Cerebral Cortex; Electrodes, Implanted; Electroencephalography; Glucose; Glycogen; Hypothalamus; Hypoxia; Ischemia; Lactates; Male; Phosphocreatine; Pyruvates; Rats; Telemetry; Time Factors

Topics: Adenine Nucleotides; Adenosine Monophosphate; Adenosine Triphosphate; Aerobiosis; Anaerobiosis; Animals; Dogs; Glucose; Glycogen; Ischemia; Kidney; Lactates; Oxygen; Phosphocreatine; Tissue Preservation

Topics: Adenosine; Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Cell Membrane Permeability; Coronary Vessels; Dogs; Heart; Hypoxanthines; Hypoxia; Inosine; Ischemia; Lactates; Myocardium; Phosphocreatine; Piperazines; Vasodilator Agents

Topics: Adenosine Triphosphate; Animals; Brain; Cerebral Cortex; Chick Embryo; Creatine; Electroencephalography; Glucose; Glucosephosphates; Glycogen; Glycolysis; Ischemia; Lactates; Mice; Phosphocreatine; Pyruvates

Topics: Adenosine Triphosphate; Anaerobiosis; Animals; Blood Glucose; Blood-Brain Barrier; Brain; Fluorometry; Fructose; Glucose; Glycogen; Hexokinase; Hypoglycemia; Hypoxia; Insulin; Ischemia; Kinetics; Mice; Permeability; Phosphocreatine

Topics: Adenine Nucleotides; Age Factors; Anaerobiosis; Animals; Animals, Newborn; Brain Chemistry; Glycogen; Glycolysis; Hypoxia; Ischemia; Kidney; Myocardium; Oxygen Consumption; Phosphocreatine; Rabbits

Topics: Adenosine Triphosphate; Animals; Blood Glucose; Glucose; Glycogen; Hypoxia; Insulin; Insulin Secretion; Ischemia; Islets of Langerhans; Male; Phosphocreatine; Rats; Tolbutamide

Topics: Adenine Nucleotides; Adenosine Triphosphate; Animals; Arteries; Blood Pressure; Body Temperature; Carbon Dioxide; Cardiac Surgical Procedures; Extracorporeal Circulation; Glycogen; Heart; Heart Arrest; Heart Arrest, Induced; Heart-Lung Machine; Hydrogen-Ion Concentration; Hypothermia, Induced; Ischemia; Lactates; Methods; Myocardium; Phosphates; Phosphocreatine; Potassium; Rabbits; Respiration, Artificial; Resuscitation; Time Factors

Topics: Adenosine Triphosphate; Animals; Brain; Brain Chemistry; Fluorometry; Freezing; Glucose; Glycogen; Hypoxia; Ischemia; Lactates; Male; Mice; Phosphocreatine; Seizures; Time Factors

Topics: Acetoacetates; Acyltransferases; Adenocarcinoma; Adenosine Triphosphate; Animals; Fatty Acids, Nonesterified; Glucose; Glucose-6-Phosphatase; Glucosephosphate Dehydrogenase; Glutamates; Glycolysis; Hydroxybutyrate Dehydrogenase; Hydroxybutyrates; Iodoacetates; Ischemia; Ketone Bodies; Kidney; Kidney Neoplasms; Lactates; Malates; NAD; Neoplasms, Experimental; Oxidoreductases; Phosphocreatine; Pyruvates; Rats; Transferases

Topics: Adenosine Triphosphate; Animals; Fluorometry; Glucose; Glycogen; Ischemia; Lactates; Male; Muscle Denervation; Muscles; Oxygen Consumption; Phosphates; Phosphocreatine; Rats

Topics: Adenine Nucleotides; Adenosine Triphosphate; Anesthetics; Animals; Cerebral Cortex; Chloral Hydrate; Chlorobutanol; Cyanides; Depression, Chemical; Electroencephalography; Ethers; Female; Guinea Pigs; Hexobarbital; Ischemia; Male; Membrane Potentials; Methoxyflurane; Pentobarbital; Phenobarbital; Phosphates; Phosphocreatine; Propanidid; Rats; Urethane

Topics: Adenosine Triphosphate; Animals; Animals, Newborn; Blood Glucose; Brain; Cerebrovascular Disorders; Glucose; Glycogen; Hexosephosphates; Hypoxia, Brain; Ischemia; Lactates; Mice; Phosphocreatine

Topics: Adenosine Diphosphate; Adenosine Triphosphate; Animals; Biopsy; Coronary Disease; Coronary Vessels; Creatine Kinase; Dogs; Energy Transfer; Heart; Ischemia; Kinetics; Lactates; Ligation; Mitochondria, Muscle; Myocardial Infarction; Myocardium; Phosphocreatine; Pyruvates

Topics: Adenine Nucleotides; Adenosine Triphosphate; Animals; Brain; Cerebellum; Cerebral Cortex; Creatine; Diencephalon; Glucose; Glycogen; Glycolysis; Ischemia; Medulla Oblongata; Mesencephalon; Phosphocreatine; Rabbits

Topics: Adenine Nucleotides; Adenosine Triphosphate; Animals; Blood Pressure; Brain; Cerebral Cortex; Diencephalon; Electroencephalography; Glucose; Glycogen; Ischemia; Lactates; Medulla Oblongata; Mesencephalon; Phosphocreatine; Rabbits; Time Factors

Topics: Adenosine Triphosphatases; Animals; Energy Transfer; Ischemia; Lactates; Muscles; Muscular Diseases; Phosphocreatine; Physical Exertion; Rabbits; Regional Blood Flow

Topics: Adenosine Triphosphate; Anesthesia; Animals; Coronary Vessels; Dogs; Ethyl Ethers; Halothane; Heart Arrest; Ischemia; Myocardium; Pentobarbital; Phosphocreatine; Resuscitation; Time Factors

Topics: Adenosine Triphosphate; Animals; Animals, Newborn; Brain; Brain Chemistry; Glucose; Glycogen; Glycolysis; Hexosephosphates; Ischemia; Lactates; Methods; Mice; Phosphocreatine

Topics: Adenine Nucleotides; Adenosine Triphosphate; Anesthesia; Animals; Brain; Brain Chemistry; Glucose; Glycogen; Hyperbaric Oxygenation; Ischemia; Lactates; Oxygen Consumption; Phosphocreatine; Rats

Topics: Adenosine Triphosphate; Animals; Chlorothiazide; Diabetes Mellitus, Experimental; Glucose; Glycogen; Hexosephosphates; Insulin; Ischemia; Kidney; Lactates; Male; Organomercury Compounds; Phlorhizin; Phosphocreatine; Rats; Starvation

Topics: Adenine Nucleotides; Adenosine Triphosphate; Animals; Blood Pressure Determination; Electrocardiography; Heart; Heart Rate; Hypoxia; In Vitro Techniques; Ischemia; Lactates; Myocardium; Oxygen Consumption; Perfusion; Phosphates; Phosphocreatine; Pyruvates; Rats

Topics: Adenine Nucleotides; Adenosine Triphosphate; Animals; Blood Flow Velocity; Coronary Disease; Coronary Vessels; Guinea Pigs; Heart; Humans; Ischemia; Isotonic Solutions; Myocardium; Nitrogen; Oxygen; Oxygen Consumption; Perfusion; Phosphocreatine

Topics: Adenine Nucleotides; Adenosine Triphosphate; Brain; Brain Neoplasms; Fluorometry; Frontal Lobe; Glioma; Glucose; Glycogen; Glycolysis; Hexoses; Humans; In Vitro Techniques; Ischemia; Lactates; Phosphocreatine; Spectrophotometry; Tissue Extracts

Topics: Adenosine Triphosphate; Animals; Clinical Enzyme Tests; Cochlea; Glucose; Glycogen; Guinea Pigs; Histocytochemistry; Hypoxia; Ischemia; NAD; NADP; Organ of Corti; Phosphates; Phosphocreatine

Topics: Adenosine Triphosphate; Animals; Brain Neoplasms; Creatine Kinase; Glioblastoma; Glucose; Glucosephosphate Dehydrogenase; Glucosyltransferases; Glutamate Dehydrogenase; Glycogen; Glycolysis; Hexokinase; Histocytochemistry; Ischemia; Lactates; Mice; NAD; NADP; Neoplasms, Experimental; Phosphates; Phosphocreatine; Phosphoglucomutase; Phosphogluconate Dehydrogenase

Topics: Adenine Nucleotides; Adenosine Triphosphate; Animals; Cats; Cholecystokinin; Glucose; Glycogen; Ischemia; Lactates; Pancreas; Pancreatic Juice; Phosphocreatine; RNA; Secretin

Topics: Adenosine Triphosphate; Brain Neoplasms; Coenzymes; Glucose; Glycogen; Glycolysis; Hexosephosphates; Ischemia; Lactates; Phosphates; Phosphocreatine; Research

Topics: Adenine Nucleotides; Adenosine Triphosphate; Animals; Brain; Decerebrate State; Dry Ice; Hypothermia, Induced; Ischemia; Phosphocreatine; Rabbits

Topics: Adenine Nucleotides; Adenosine Triphosphate; Animals; Axons; Carbohydrate Metabolism; Fructose; Glucose; Glycogen; Hypoxia; In Vitro Techniques; Ischemia; Lactates; Nerve Degeneration; Nervous System Diseases; Neurilemma; Oxygen Consumption; Peripheral Nerves; Phosphates; Phosphocreatine; Rabbits; Schwann Cells

Topics: Adenine Nucleotides; Adenosine Triphosphate; Animals; Brain Chemistry; Cats; Cerebral Cortex; Creatine; Glycolysis; In Vitro Techniques; Ischemia; Oxidative Phosphorylation; Oxygen Consumption; Pentobarbital; Phenobarbital; Phosphocreatine

Topics: Adenine Nucleotides; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Coenzymes; Creatine Kinase; Eye Diseases; Ischemia; Lacrimal Apparatus; Lactates; Lagomorpha; Liver; Metabolism; NAD; Oxidation-Reduction; Phosphocreatine; Phosphorylation; Pyruvates; Rabbits; Research

The results reported in this paper indicate that dinitrophenol acts directly on the isolated heart, increasing its metabolic rate. It also produces heart failure associated with a low phosphocreatine content of the muscle but with no change in adenosine triphosphate, which may or may not be due to a relative hypoxia of the cardiac tissue. Experimental arterial hypoxaemia, if severe, produces a similar picture of heart failure with a decrease in phosphocreatine and no change in adenosine triphosphate. Ligation of the coronary arteries results in disappearance of the major part of the phosphocreatine within a few minutes regardless of whether or not ventricular fibrillation ensues; the adenosine triphosphate remains unchanged.

Topics: Adenosine Triphosphate; Animals; Blood Circulation; Coronary Vessels; Dinitrophenols; Dogs; Heart; Heart Failure; Humans; Hypoxia; Ischemia; Myocardium; Nitrophenols; Phosphocreatine; Phosphorus; Phosphorus Compounds