phosphocreatine and Nutrition-Disorders

Metabolic alterations in skeletal muscle associated with malnutrition and the potential reversibility of such alterations during refeeding are not fully understood.. We characterized early changes in muscle during refeeding in malnourished, hospitalized elderly subjects.. Muscle function, metabolism, and mass were evaluated in 24 clinically stable patients (11 were malnourished) by using isokinetic plantar flexor torque measurements and nuclear magnetic resonance (NMR) imaging for medial gastrocnemius mass assessment and 31P and 13C NMR spectroscopy for inorganic phosphate (Pi), phosphocreatine, and glycogen quantitation.. Malnourished subjects had lower muscle mass (P < 0.02) and tended to have lower strength than did control subjects. In malnourished subjects, muscle strength increased after refeeding (P < 0.01) whereas muscle mass was unchanged. The ratio of Pi to ATP was lower in malnourished than in control subjects (P < 0.001) and increased during refeeding (P < 0.01). The mean ratio of phosphocreatine to ATP was lower in malnourished than in control subjects (P < 0.01) and increased to control values after refeeding. Muscle glycogen showed a scattered distribution for malnourished subjects; the mean value did not differ significantly from that of control subjects, either at baseline or after refeeding.. The lower ratio of phosphocreatine to ATP in malnourished subjects could have resulted from either lower total muscle creatine or reduced oxidative capacities. High or normal glycogen associated with a low Pi-to-ATP ratio in malnourished subjects suggested preferential use of lipid over carbohydrate for energy supply, which is known to reduce muscle performance. The data suggest that normalization of muscle metabolite content after refeeding improves muscle strength in malnourished subjects.

Topics: Adenosine Triphosphate; Aged; Aged, 80 and over; Aging; Carbon Isotopes; Female; Glycogen; Hospitalization; Humans; Magnetic Resonance Spectroscopy; Male; Muscle, Skeletal; Nutrition Disorders; Nutritional Status; Phosphates; Phosphocreatine; Phosphorus Isotopes

We investigated the relationship between nutritional status and muscle energy metabolism during exercise in 18 male patients with chronic obstructive pulmonary disease (COPD) and 15 male control subjects using 31P nuclear magnetic resonance spectroscopy (31P-MRS). The patients and control subjects were further categorized as in either a well-nourished (% ideal body weight, % IBW > or = 90) or malnourished (% IBW < 90) state. Muscle energy metabolism was evaluated by determining the ratios PCr/(PCr + Pi) (PCr, phosphocreatine; Pi, inorganic phosphate), and ATP/(PCr + Pi + ATP). The exercise consisted of repetitive hand grips performed against a load. The work rate was normalized for the individual's lean muscle mass by dividing work performed by the forearm fat-free cross-sectional area, which was calculated using 1H-MRS. The PCr/(PCr + Pi) values during exercise did not correlate with the % IBW in any of the groups of control subjects or COPD patients. Furthermore, the PCr/(PCr + Pi) did not correlate with the normalized work rate in either the well-nourished or malnourished subject groups. However, there were correlations within the groups of control subjects and COPD patients. The PCr/(PCr + Pi) values for the normalized work rate were consistently lower in the COPD patients than in the control subjects. These findings suggest that the altered muscle metabolism in COPD patients is not affected by their nutritional status.

Topics: Adenosine Triphosphate; Adult; Aged; Body Weight; Case-Control Studies; Energy Metabolism; Hand; Humans; Hydrogen; Lung Diseases, Obstructive; Magnetic Resonance Spectroscopy; Male; Middle Aged; Muscle Contraction; Muscle, Skeletal; Nutrition Disorders; Nutritional Status; Phosphates; Phosphocreatine; Phosphorus; Physical Exertion; Weight Lifting; Work

Malnutrition has been associated with changes in cardiac metabolism and performance. We have previously reported a diabetic-type cardiomyopathy associated with chronic food restriction and weight loss. Because the creatine-phosphocreatine-creatine kinase system is important in the contractile process, we studied the components of this system in rats fed a food-restricted diet (33% of control animal intake). After 4 weeks of food restriction, total creatine kinase (CK) activities were reduced by 28% in ventricles and by 38% in atria. The CK isoenzymes in the heart were not equally affected. The BB isoenzyme was decreased by 77% and 78%, the MB isoenzyme by 45% and 43%, the MM isoenzyme by 22% and 19% and CKmito by 16% and 15% in ventricles and atria, respectively. In contrast, brain CK activity which is predominantly the BB isoenzyme, was slightly higher in the food-restricted than in control rats. Further studies on ventricular tissue from food-restricted rats revealed a 27% decline in myofibrillar CR activity and a 58% decline in myofibrillar ATPase activity. Phosphocreatine and creatine concentrations were not changed by food restriction, however, ATP was decreased by 23% in ventricles from rats on the restricted diet. Cardiac mitochondrial oxidative phosphorylation was also impaired. State 3 respiration with alpha-ketoglutarate was reduced 20% in the food-restricted heart. These changes are compared to those which we previously observed in the diabetic rat heart and the significance of these findings is discussed.

Topics: Adenosine Triphosphatases; Adenylate Kinase; Animals; Creatine Kinase; Energy Metabolism; Food Deprivation; Isoenzymes; Male; Mitochondria, Heart; Myocardium; Nutrition Disorders; Oxidative Phosphorylation; Phosphocreatine; Rats; Rats, Sprague-Dawley

1. Intramuscular concentrations of adenosine 5'-triphosphate (ATP) and creatine phosphate were measured in the vastus lateralis muscle of 28 non-septic malnourished patients and 31 septic malnourished patients. Similar measurements were made on the rectus abdominis muscle of about one-third of these patients. All results were compared with those obtained from 15 normally nourished non-septic control subjects. 2. Objective measurements of nutritional status (both anthropometric and biochemical) and sepsis were recorded in all subjects. 3. The vastus lateralis muscle of the non-septic and septic malnourished patients had intramuscular concentrations of ATP and total adenine nucleotides (TAN) that were up to 30% lower than control values, depending on the reference base used. 4. In the rectus abdominis muscle, ATP and TAN concentrations were up to 60% lower than control values, and creatine phosphate up to 47% lower, again depending on the reference base used. 5. In both muscles, the changes were more marked in those patients who were septic as well as malnourished.

Topics: Adenosine Triphosphate; Adult; Aged; Aged, 80 and over; Bacterial Infections; Humans; Middle Aged; Muscles; Nutrition Disorders; Phosphocreatine

The in vivo incorporation of radioactivity from [U-14C]glucose was reduced in undernourished rat pups at ages 6, 10, and 17 days for brain lipids, and at age 10 days for brain amino acids. Brain glucose concentrations were lower at age 20 days (controls 1.58 +/- 0.26 vs. test 1.14 +/- 0.07 mumol/g) but other alterations in brain glucose, glycogen, ATP, or phosphocreatine concentrations were not found. Brain mitochondrial glutamate dehydrogenase activity was 21% and 30% lower in undernourished animals at ages 10 and 20 days, respectively. Brain mitochondrial and supernatant isocitrate dehydrogenase activities and pyruvate kinase activity were similar for undernourished and control animals. Brain glycogen levels were 2-4 times higher in late fetal and newborn control animals (13.6 and 15.3 mumol/g) than in older animals (4.2-5.7 mumol/g). Brain glucose, ATP, and phosphocreatine levels increased from the 15-day fetus to the newborn, but thereafter showed no further increase.

Topics: Adenosine Triphosphate; Amino Acids; Animals; Body Weight; Brain; Glucose; Glutamate Dehydrogenase; Glycogen; Lipid Metabolism; Mitochondria; Nutrition Disorders; Organ Size; Phosphocreatine; Rats

Topics: Adenosine Triphosphate; Aminobutyrates; Animals; Animals, Newborn; Aspartic Acid; Body Weight; Brain; Centrifugation; DNA; Fluorometry; Glucose; Glutamates; Glycogen; Lactates; Liver; Nerve Tissue Proteins; Nutrition Disorders; Phenylalanine; Phosphates; Phosphocreatine; Phosphorus; Rats; RNA; Spectrophotometry