phosphocreatine and Diabetes-Mellitus--Type-1

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

Diabetic cardiomyopathy (DCM) is one of the common cardiovascular complications in patients with diabetes. Accumulating evidence has demonstrated that DCM is thoroughly related to mitochondrial energy impairment and increases the generation of reactive oxygen species (ROS). Therefore, an ongoing study is developing strategies to protect cardiac mitochondria from diabetic complications, especially from hyperglycemia. Phosphocreatine (PCr) plays a major metabolic role in cardiac muscular cells including intracellular concentration of ATP which affects the activity of the myocardium. We hypothesized that PCr might improve oxidative phosphorylation and electron transport capacity in mitochondria impaired by hyperglycemia in vivo and in vitro. Also, we aimed to evaluate the protective effect of PCr against DCM through the JAK2/STAT3 signaling pathway. The mitochondrial respiratory capacity from rats and H9C2 cells was measured by high-resolution respirometry (HRR). Expressions of proteins Bax, Bcl-2, caspase 3, caspase 9, cleaved caspase 3, and cleaved caspase 9, as well as JAK2/STAT3 signaling pathways, were determined by western blotting. ROS generation and mitochondrial membrane potential (MMP) were measured with fluorescent probes. Type 1 diabetes mellitus was induced in Wistar male rats by a single intraperitoneal injection of streptozotocin (STZ) (80 mg/kg body weight). Our results revealed that PCr possessed protective effects against DCM injury by improving the mitochondrial bioenergetics and by positively exerting protective effects against DCM in vivo and in vitro, not only improving diabetes symptom, resulting in changes of cardiac tissue using hematoxylin and eosin (H&E) stain, but also ameliorating biochemical changes. Moreover, PCr increased Bcl-2, caspase 3, and caspase 9 protein expressions and decreased Bax, cleaved caspase 3, and cleaved caspase 9 expressions as well as the JAK2/STAT3 signaling pathway. In conclusion, PCr improves mitochondrial functions and exerts an antiapoptotic effect in vivo and in vitro exposed to oxidative stress by hyperglycemia through the JAK2/STAT3 signaling pathway. Our findings suggest that PCr medication is a possible therapeutic strategy for cardioprotection.

Topics: Animals; Cell Line; Cell Respiration; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Diabetic Cardiomyopathies; Humans; Janus Kinase 2; Male; Membrane Potential, Mitochondrial; Mitochondria, Heart; Myocardium; Phosphocreatine; Rats; Rats, Wistar; Reactive Oxygen Species; Signal Transduction; STAT3 Transcription Factor

This study was performed to assess left ventricular (LV) energy metabolism and function in patients with type 1 diabetes with or without overt microvascular complications.. We performed cardiac Magnetic Resonance Imaging (MRI) and (31)P spectroscopy (MRS) in 24 patients with overt microvascular complications and in 15 carefully selected patients without complications in spite of a long duration of the disease (>20 years) and matched for anthropometric features. 31 healthy subjects served as a control group.. Systolic function was preserved in all study subjects. Patients with overt complications showed a higher LV wall mass/end diastolic volume ratio and altered parameters of diastolic function when compared to patients without complications and to controls. They were also characterized by lower PCr/ATP ratio (a recognized marker of energy metabolism). No effect of HbA1c was detected within groups.. In patients with type 1 diabetes 1) overt microvascular complications were associated with altered LV geometry, diastolic function and energy metabolism 2) in patients without complications and duration of disease >20 years no association with these alterations were found despite poor glycemic control. The features of this highly selected subgroup of patients demonstrated that long lasting chronic hyperglycemia per se is not sufficient to induce abnormality of cardiac energy metabolism and that additional yet to be identified (metabolic or genetic) factors must be important contributing factors.

Topics: Adenosine Triphosphate; Adult; Blood Glucose; Diabetes Mellitus, Type 1; Diabetic Angiopathies; Diastole; Energy Metabolism; Fatty Acids; Female; Homeostasis; Humans; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Male; Microcirculation; Middle Aged; Phosphocreatine; Systole; Ventricular Function, Left

Nitrosative stress, that is, enhanced peroxynitrite formation, has been documented in both experimental and clinical diabetic neuropathy (DN), but its pathogenetic role remains unexplored. This study evaluated the role for nitrosative stress in two animal models of type 1 diabetes: streptozotocin-diabetic mice and diabetic NOD mice. Control (C) and streptozotocin-diabetic (D) mice were treated with and without the potent peroxynitrite decomposition catalyst FP15 (5 mg kg(-1) d(-1)) for 1 wk after 8 wk without treatment. Sciatic nerve nitrotyrosine (a marker of peroxynitrite-induced injury) and poly(ADP-ribose) immunoreactivities were present in D and absent in C and D+FP15. FP15 treatment corrected sciatic motor and hind-limb digital sensory nerve conduction deficits and sciatic nerve energy state in D, without affecting those variables in C. Nerve glucose and sorbitol pathway intermediate concentrations were similarly elevated in D and D+FP15 vs C. In diabetic NOD mice, a 7-day treatment with either 1 or 3 mg kg(-1) d(-1) FP15 reversed increased tail-flick latency (a sign of reduced pain sensitivity); the effect of the higher dose was significant as early as 3 days after beginning of the treatment. In conclusion, nitrosative stress plays a major role in DN in, at least, type 1 diabetes. This provides the rationale for development of agents counteracting peroxynitrite formation and promoting peroxynitrite decomposition, and their evaluation in DN.

Topics: Animals; Blood Glucose; Creatine; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Diabetic Neuropathies; Metalloporphyrins; Mice; Mice, Inbred NOD; Neural Conduction; Neurons, Afferent; Oxidative Stress; Peroxynitrous Acid; Phosphocreatine; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerases; Reactive Nitrogen Species; Sciatic Nerve; Tyrosine; Weight Gain

To test whether left ventricular (LV) dysfunction affecting type 1 diabetic-uremic patients was associated with abnormal heart high-energy phosphates (HEPs) and to ascertain whether these alterations were also present in recipients of kidney or kidney-pancreas transplantation.. Heart failure is the major determinant of mortality in patients with diabetic uremia. Both uremia and diabetes induce alterations of cardiac HEPs metabolism.. Magnetic resonance imaging and phosphorous magnetic resonance spectroscopy of the LV were performed in the resting state by means of a 1.5-T clinical scanner. Eleven diabetic-uremic patients, 5 nondiabetic patients with uremia, 11 diabetic recipients of kidney transplantation, and 16 diabetic recipients of combined kidney-pancreas transplantation were studied in a cross-sectional fashion. Eleven nondiabetic recipients of kidney-only transplant and 13 healthy subjects served as control groups.. Uremic patients had higher LV mass, diastolic dysfunction, and lower phosphocreatine (PCr)/adenosine triphosphate (ATP) ratio in comparison with recipients of kidney-pancreas or nondiabetic recipients of kidney transplant. In diabetic recipients of kidney transplant the PCr/ATP ratio was higher than in uremic patients but was lower than in the controls. Recipients of combined kidney-pancreas transplant had a higher ratio than uremic patients but no difference was found in comparison with controls.. Altered resting myocardial HEPs metabolism may contribute to LV dysfunction in diabetic-uremic patients. In diabetic recipients of kidney transplantation, a certain degree of LV metabolic and functional impairment was found. In combined kidney-pancreas recipients the resting LV metabolism and function were not different than in controls.

Topics: Adenosine Triphosphate; Aged; Cross-Sectional Studies; Diabetes Complications; Diabetes Mellitus, Type 1; Energy Metabolism; Female; Heart Ventricles; Humans; Kidney Transplantation; Magnetic Resonance Spectroscopy; Male; Middle Aged; Pancreas Transplantation; Phosphocreatine; Phosphorus Isotopes; Uremia; Ventricular Dysfunction, Left

This study aimed to examine brain energy metabolism during moderate insulin-induced hypoglycaemia in Type 1 diabetic patients and healthy volunteers.. Type 1 diabetic patients (mean diabetes duration 13 +/- 2.5 years; HbA1c 6.8 +/- 0.3%) and matched controls were studied before, during (0-120 min) and after (120-240 min) hypoglycaemic (approximately 3.0 mmol/l) hyperinsulinaemic (1.5 mU x kg(-1) min(-1)) clamp tests. Brain energy metabolism was assessed by in vivo 31P nuclear magnetic resonance spectroscopy of the occipital lobe (3 Tesla, 10-cm surface coil).. During hypoglycaemia, the diabetic patients showed blunted endocrine counter-regulation. Throughout the study, the phosphocreatine:gamma-ATP ratios were lower in the diabetic patients (baseline: controls 3.08 +/- 0.29 vs diabetic patients 2.65 +/- 0.43, p<0.01; hypoglycaemia: 2.97 +/- 0.38 vs 2.60 +/- 0.35, p<0.05; recovery: 3.01 +/- 0.28 vs 2.60 +/- 0.35, p<0.01). Intracellular pH increased in both groups, being higher in diabetic patients (7.096 +/- 0.010 vs. 7.107 +/- 0.015, p<0.04), whereas intracellular magnesium concentrations decreased in both groups (controls: 377 +/- 33 vs 321 +/- 39; diabetic patients: 388 +/- 47 vs 336 +/- 68 micromol/l; p<0.05).. Despite a lower cerebral phosphocreatine:gamma-ATP ratio in Type 1 diabetic patients at baseline, this ratio does not change in control or diabetic patients during modest hypoglycaemia. However, both groups exhibit subtle changes in intracellular pH and intracellular magnesium concentrations.

Topics: Adenosine Triphosphate; Adult; Blood Glucose; Brain Chemistry; Diabetes Mellitus, Type 1; Energy Metabolism; Glucose Clamp Technique; Hormones; Humans; Hypoglycemia; Magnetic Resonance Spectroscopy; Male; Phosphocreatine

Phosphor-31 two-dimensional chemical shift imaging (3lP 2-D CSI) is a well-established noninvasive technique in experimental research on regional myocardial ischemia, and it permits in vivo monitoring of high-energy phosphate metabolism in the myocardium without requiring external tracers,wherein phosphocreatinine (PCr) and beta-adenosine triphosphate (beta-ATP) are the main components of investigation. The decrease of PCr is one of the earliest reactions to acute myocardial ischemia, but also fixed defects after myocardial infarction (MI) showed a reduced ratio of PCr/beta-ATP, probably because of are modeling process taking place in the noninfarcted tissue.. A 55-year-old patient with diabetes mellitus type 1 is reported, who presented within the scope of a study at the University Hospital Innsbruck, Austria, and in whom 31P 2-D CSI helped to detect a so far unknown coronary heart disease (CHD).. In the presented case, 31P 2-D CSI for the first time helped to reveal a severe CHD and a so far unknown MI,and and if the calculated voxel size was chosen small enough, even a satisfying localization of the lesion became possible.

Topics: Adenosine Triphosphate; Diabetes Mellitus, Type 1; Electrocardiography; Humans; Magnetic Resonance Imaging, Cine; Male; Middle Aged; Myocardial Infarction; Myocardium; Phosphates; Phosphocreatine; Phosphorus Isotopes

To investigate whether alterations in high-energy phosphates occur in the myocardium of persons with diabetes mellitus type I. Microvascular abnormalities and dysfunction via thickening of the basement membrane are known to occur in diabetic patients. Myocardial high-energy phosphates have been shown to be reduced by ischemia, and alterations of the cardiac metabolism are the primary consequence of myocardial ischemia.. The present study involved 34 male patients (mean age 35.5 +/- 10.1) with diabetes mellitus type I and 35 healthy male volunteers (mean age 36 +/- 8.6) as age-matched controls. Phosphorus-31 magnetic resonance spectroscopic imaging of the heart was performed in all subjects using a 1.5-T whole-body magnetic resonance scanner. The ratios of phosphocreatine (PCr) to beta-adenosinetriphosphate (beta-ATP) were calculated. Moreover, echocardiographic evaluation and stress tests were performed in all individuals.. The myocardium of patients with diabetes mellitus type I showed significantly decreased ratios of PCr to beta-ATP compared with healthy controls in the left ventricle (1.90 +/- 0.4 vs. 2.15 +/- 0.3, p < 0.05). We found a moderate negative correlation between the ratio of PCr to beta-ATP in the left ventricle and both, the diastolic left ventricular function (E/A; r = -0.41) and the glycohemoglobin A1c (GHbA1c; r = -0.42).. This study demonstrates for the first time a decreased ratio of PCr to beta-ATP in the myocardium of persons with diabetes mellitus type I without a known history of coronary heart disease.

Topics: Adenosine Triphosphate; Adult; Biomarkers; Case-Control Studies; Data Interpretation, Statistical; Diabetes Mellitus, Type 1; Echocardiography; Exercise Test; Glycated Hemoglobin; Heart Ventricles; Humans; Magnetic Resonance Spectroscopy; Male; Middle Aged; Myocardium; Phosphocreatine; Phosphorus Isotopes; Ventricular Dysfunction, Left

It has been previously suggested that alterations in sodium homeostasis, leading to calcium overload may play a part in the mediation of cardiac ischemic injury. It has been demonstrated that the Na+-H+ exchanger plays an important role with regard to the regulation of intracellular sodium during ischemia and reperfusion and that inhibition of the Na+-H+ exchanger during ischemia protects hearts from ischemic injury. Studies using chemically-induced diabetic animals have suggested that the cardiac Na+-H+ exchanger in the diabetic heart is impaired and is responsible for limiting the increase in sodium during ischemia. The extent to which the Na+-H+ exchanger contributes to increases in intracellular sodium during ischemia in diabetic hearts is unclear as direct measurements of exchanger activity have not been made in genetically diabetic hearts. Therefore, this paper aims to address the following issues: (a) is the Na+-H+ exchanger impaired in a genetically diabetic rat heart: (b) does this impairment result in lower [Na]i or [Ca]i during ischemia; and (c) does Na+-H+ exchanger inhibition limit injury and functional impairment in diabetic hearts during ischemia and reperfusion? These issues were examined by inhibiting the Na+-H+ exchanger with ethylisopropylamiloride (EIPA) in isolated perfused hearts from both genetically diabetic (BB/W) and non-diabetic rats. Levels of intracellular sodium, intracellular calcium, intracellular pH and high energy phosphates (using 23Na,19F, 31P NMR spectroscopies, respectively) during global ischemia and reperfusion were also measured. The impact of diabetes on Na+-H+ exchanger activity was assessed by measuring pH recovery of these hearts after an acid load. Creatine kinase release during reperfusion was used as a measure of ischemic injury. This study demonstrated that the Na+-H+ exchanger is impaired in diabetic hearts. Despite this impaired activity, inhibition of Na+-H+ exchanger protected diabetic hearts from ischemic injury and was associated with attenuation of the rise in sodium and calcium, and limitation of acidosis and preservation of ATP during ischemia. The data presented here favor the use of Na+-H+ exchanger inhibitors to protect ischemic myocardium in diabetics. Also, the data provides possible mechanisms for the altered susceptibility of diabetic hearts to ischemic injury.

Topics: Acidosis; Adenosine Triphosphate; Amiloride; Animals; Calcium; Diabetes Mellitus, Type 1; Hydrogen-Ion Concentration; In Vitro Techniques; Intracellular Fluid; Magnetic Resonance Spectroscopy; Myocardial Reperfusion Injury; Phosphocreatine; Quaternary Ammonium Compounds; Rats; Rats, Inbred BB; Sodium; Sodium-Hydrogen Exchangers

In spontaneously diabetic BB rats, the effect of chronically maintained blood glucose levels on the degree of energy failure and brain pH change during an ischemic insult, and on subsequent recovery after reperfusion, was studied with in vivo 31P magnetic resonance spectroscopy. Short duration forebrain ischemia (10-min carotid occlusion plus hypotension of 50 mmHg) was induced in diabetic and nondiabetic male BB rats whose blood glucose levels were maintained with insulin. Spectra were obtained in 1-min blocks before, during, and for 1 h after ischemia. Before ischemia, hypoglycemic (blood glucose less than 3 mM) diabetic rats had an increased Pi peak intensity, with no significant pH change, compared with other groups. During ischemia, the rate and extent of hydrolysis of high-energy phosphate metabolites (as measured by an increase in Pi) decreased, and the severity of tissue acidosis increased as preischemia blood glucose concentration increased. Among hyperglycemic BB rats, similar ischemia-induced changes were found for subgroups with blood glucose levels of 13.7 +/- 1.2 and 20.3 +/- 0.6 mM, in keeping with the known decrease in hexose binding sites associated with chronic hyperglycemia. Decline in PCr level during ischemia was not significantly different between groups. With reperfusion, both Pi and pH values rapidly returned to preischemia values. PCr levels, however, did not recover in hyperglycemic diabetic animals, with the degree of residual impairment dependent on the preischemia glucose level. Results suggest that optimal management of diabetes may lessen the degree of injury within the ischemic penumbra in diabetic patients who suffer a stroke.

Topics: Analysis of Variance; Animals; Blood Glucose; Blood Pressure; Diabetes Mellitus, Type 1; Hydrogen-Ion Concentration; Ischemic Attack, Transient; Magnetic Resonance Spectroscopy; Male; Phosphocreatine; Phosphorus; Prediabetic State; Prosencephalon; Rats; Rats, Inbred BB; Reperfusion

An hypothesis is presented relating several well-defined metabolic abnormalities in diabetic peripheral nerve to impaired peripheral nerve function by a sodium-potassium ATPase mechanism. It is proposed that this hypothesis be tested in the most well-defined animal model for human insulin deficiency diabetes currently available--the BB diabetic rat.

Topics: Animals; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Energy Metabolism; Female; Glucose; Hyperglycemia; Inositol; Male; Peripheral Nerves; Phosphocreatine; Rats; Rats, Inbred Strains; Sodium-Potassium-Exchanging ATPase