The pattern of cytosolic ADP recovery after exercise has not been fully characterized in human skeletal muscle. ADP recovery after brief, ischemic exercise was studied by 31phosphorus magnetic resonance spectroscopy in calf muscles of 33 normal control subjects, four patients with McArdle's disease and 13 patients with mitochondrial myopathy. In ...

Impairment of muscle glycogenolysis in McArdle's disease (myophosphorylase deficiency) leads to exercise intolerance and exercise-induced myalgia. The pathophysiology of these symptoms is not entirely clear. We used phosphorus magnetic resonance spectroscopy to measure muscle phosphate metabolite concentrations and intracellular pH during brief ischemic exercise and in the period of aerobic ...

Metabolic changes measured by 31P-magnetic resonance spectroscopy and surface electromyograms were simultaneously recorded during isometric contraction of forearm flexor muscles sustained at 60% of maximal force until exhaustion. Throughout the fatigue trial, energy in the low-frequency (L) band continuously increased whereas energy in the high-frequency (H) band first increased and ...

The purpose of this study was to determine if chronic fatigue syndrome (CSF) is characterized by abnormalities in oxidative muscle metabolism. Patients with CFS according to Centers for Disease Control (CDC) criteria (n = 22) were compared to normal sedentary subjects (n = 15). CFS patients were also tested before ...

After erythropoietin (rHuEPO) therapy, patients with chronic renal failure (CRF) do not improve peak O2 uptake (VO2 peak) as much as expected from the rise in hemoglobin concentration ([Hb]). In a companion study, we explain this phenomenon by the concurrent effects of fall in muscle blood flow after rHuEPO and ...

The effects of exercise (swimming), fatigue, and recovery on the intracellular pH (pHi), energy-rich phosphates, and related metabolites were studied in the gastrocnemius muscle of common frogs (Rana temporaria) at 20 degrees C. Exercise caused a rapid decrease in the content of phosphocreatine (PCr) and a corresponding increase in that ...

Of all humans thus far studied, Sherpas are considered by many high-altitude biomedical scientists as most exquisitely adapted for life under continuous hypobaric hypoxia. However, little is known about how the heart is protected in hypoxia. Hypoxia defense mechanisms in the Sherpa heart were explored by in vivo, noninvasive 31P ...

Six male long-distance runners performed knee flexion exercises in a 2.1 T superconducting magnet. 31P MRS was used to investigate the splitting pattern of the inorganic phosphate (Pi) peak during active and passive recovery. During exercise splitting of the Pi peak into two was observed (high and low pH) and ...

This study aimed to compare the effects of oral creatine (Cr) supplementation with creatine supplementation in combination with caffeine (Cr+C) on muscle phosphocreatine (PCr) level and performance in healthy male volunteers (n = 9). Before and after 6 days of placebo, Cr (0.5 g x kg-1 x day-1), or Cr ...

Proton decoupled 31P in vivo NMR spectroscopy of the human finger flexor muscles was performed during exercise and recovery using a 1.5 T whole-body imager. Predominantly the gamma-ATP signal shows a splitting caused by different signal contributions with chemical shifts that vary independently. Studies on the human gastrocnemius and biceps ...

Energy status and metabolism in skeletal muscle of nine patients with peripheral arterial disease and suffering from intermittent claudication were evaluated using 31phosphorus magnetic resonance spectroscopy (MRS) before and after treatment for 3 months with propionyl-L-carnitine (PLC; 2 g/day p.o.). Maximum walking distance (MWD) was assessed on a standard treadmill ...

Skeletal muscle metabolism during exercise was compared in 5 patients with end-stage renal disease (ESRD) and 8 healthy controls, using a noninvasive technique, 31P magnetic resonance spectroscopy (MRS). After 3 months of anaemia correction with recombinant human erythropoietin (rHuEPO) these patients were re-evaluated. Maximal power achieved by the ESRD patients ...

31P magnetic resonance spectroscopy (MRS) was used to study an open therapeutic trial of coenzyme Q10 (CoQ) in mitochondrial encephalomyopathies. Eight patients were treated with 150 mg CoQ per day for 6 months. 31P MRS spectra of calf muscle were recorded at rest, during exercise and in the immediate postexercise ...

We measured ATP, phosphocreatine (PCr), inorganic phosphate (Pi), and the intracellular pH in rat hindlimb muscles during submaximal isometric exercise with various O2 deliveries using 31P nuclear magnetic resonance spectroscopy (31P NMR) to evaluate changes in energy metabolism in relation to O2 availability. Delivery of O2 to muscles was altered ...

1. We set out to define abnormalities of oxidative ATP synthesis, cellular proton efflux and the efficiency of ATP usage in gastrocnemius muscle of patients with claudication due to peripheral vascular disease, using data obtained by 31P magnetic resonance spectroscopy during aerobic exercise and recovery. 2. Eleven patients with moderate ...

A large number of studies have shown amplitude and spectral changes of the electromyogram during exercise, leading to several theories of how these changes might be related to the underlying metabolic changes. The amplitude and spectral changes are generally interpreted as changes in motor unit recruitment and a reduction of ...

It has been known since ancient times that turtle hearts exhibit extraordinary tolerance to anoxia or ischemia. The mechanisms by which they accomplish this remain obscure. The most important adaptation in anoxic turtles is a rapid and dramatic decrease in metabolic rate. Nuclear magnetic resonance measurements indicate that painted turtle ...

In McArdle's disease (myophosphorylase deficiency) exercise intolerance is generally attributed to a lack of glycogenolysis, which decreases energy production during exercise. Magnetic resonance imaging data have recently suggested an impairment of the increase in muscle perfusion during exercise in these patients. We have tested this hypothesis by direct measurement of ...

Magnetic resonance (MR) imaging studies of exercising leg muscles were performed to compare the changes in MR transverse relaxation times (T2) that result from exercise of the anterior tibialis (AT) and extensor digitorum/hallicus longus (E) in the anterior compartment of the lower leg with those T2 changes in the medial ...

We measured isotonic sliding distance of single skinned fibers from rabbit psoas muscle when known and limited amounts of ATP were made available to the contractile apparatus. The fibers were immersed in paraffin oil at 20 degrees C, and laser pulse photolysis of caged ATP within the fiber initiated the ...

Alternating hemiplegia of childhood is an uncommon disease characterized by repeated, transient attacks of hemiplegia. Its pathophysiology is uncertain, but attention recently has focused on possible mitochondrial abnormalities. Using 31P magnetic resonance spectroscopy, we studied gastrocnemius muscle in 5 patients with alternating hemiplegia, aged 8 to 30 (mean, 18) years, ...

BACKGROUND: Exercise intolerance in patients with cystic fibrosis is commonly attributed to reduced pulmonary and nutritional status. The possible role of diminished efficiency of mitochondrial oxidative phosphorylation in relation to skeletal muscle performance was investigated in patients with cystic fibrosis. METHODS: In vivo synthesis of ATP in skeletal muscle during ...

Local acidosis (pH 6.4) depresses reactivity of vascular smooth muscle and especially the response of human isolated saphenous veins to exogenous norepinephrine. Experiments were performed to study, under acidosis conditions, the interaction between Daflon 500 mg, a micronized fraction of 90% diosmin and 10% hesperidin, and norepinephrine on human rings ...

This brief review describes the main physicochemical factors that contribute to increases in intracellular hydrogen ion concentration ([H+]i) in mammalian skeletal muscle during high intensity exercise. High intensity exercise results in changes in the three main independent physicochemical variables: PCO2, the strong ion difference ([SID]), and total concentration of weak ...

Type II carnitine palmitoyltransferase deficiency is the most common cause of exercise-induced rhabdomyolysis, myoglobinuria, and proximal muscle weakness and pain in young adults. A lack of this enzyme impairs mitochondrial oxidation of long-chain fatty acids and can lead to rhabdomyolysis, myoglobinuria, and renal failure. Carnitine palmitoyltransferase deficiency, unusual but not ...

OBJECTIVE: To investigate whether patients with fibromyalgia (FM) have normal motor unit recruitment in relation to muscle metabolism during exhausting exercise and recovery, and whether the reduced voluntary muscle force normally seen is related to a smaller muscle size. METHODS: Female patients with FM and sedentary controls were examined using ...

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 ...

Sepsis increases phosphocreatine (PCr) breakdown and reduces PCr stores in skeletal muscle. To determine if systemic infection impairs mitochondrial function, in vivo 13P magnetic resonance spectroscopy (31P MRS) studies of the gastrocnemius muscle were performed in virus-free male Wistar rats 24 or 48 hr after cecal ligation and 18-gauge needle ...

Gastric acidosis as assessed by tonometry was applied to evaluate changes in splanchnic blood flow during exercise. In six healthy male oarsmen, we determined gastric acidosis in response to 30 min of maximal ergometer rowing. The gastric mucosa carbon dioxide tension was determined by equilibration of isotonic saline to the ...

Exercise-induced spin-spin relaxation time (T2) shifts in magnetic resonance (MR) images were used to test the hypothesis that more muscle would be used to perform a given submaximal task after 5 wk of unweighting. Before and after unilateral lower limb suspension (ULLS), 7 subjects performed 5 sets of 10 unilateral ...

In isolated hepatocytes incubated in hypoosmotic media, a large increase in the mitochondrial volume is not directly involved in the activation of respiration. Moreover, results of the quantification of the various bioenergetic parameters are not in accordance with an activation of the respiratory chain as previously proposed (Halestrap, A.P. (1989) ...

We performed a short-term, double-blind, placebo-controlled, crossover trial of sodium dichloroacetate (DCA) therapy in 11 patients affected by various primary mitochondrial disorders. Independent measures of oxidative metabolism (venous blood metabolites, exercise testing, phosphorus magnetic resonance [MR] spectroscopy of muscle, and proton MR spectroscopy of brain) were used in order to ...

Phosphocreatine (PCr) availability is likely to limit performance in brief, high-power exercise because the depletion of PCr results in an inability to maintain adenosine triphosphate (ATP) resynthesis at the rate required. It is now known that the daily ingestion of four 5-g doses of creatine for 5 days will significantly ...

By means of proton and phosphorous magnetic resonance spectroscopy at 1.5 Tesla the human cerebral metabolism was investigated during mild and moderate hypoxaemia. Seven volunteers participated and spectra were obtained while the subjects were breathing atmospheric air, 16, 12 and 10% oxygen in N2.PaO2, PCO2 and arterial oxygen saturation were ...

Patients with congestive heart failure reportedly show a poor correlation between cardiac function and exercise tolerance. Recent studies have demonstrated that skeletal muscle is the main factor that limits exercise tolerance. However, the relationship between high-energy phosphate metabolism in skeletal muscle and exercise tolerance has not been well defined. Exercise ...

Bioenergetic sufficiency can be quantitatively assayed by nuclear magnetic resonance spectroscopy (MRS) and on a relative basis by tissue optical spectroscopy (NIRS). Nuclear magnetic resonance measures quantitatively the fall of phosphocreatine and the rise of inorganic phosphate necessary to raise mitochondrial adenosine diphosphate and activate ATP synthesis to adequate level ...

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 ...

31P magnetic resonance spectroscopy (31P MRS) can yield much information about bioenergetics in skeletal muscle. During mixed aerobic/glycolytic exercise, changes in phosphocreatine (PCr) concentration and pH may be abnormal because of reduced muscle mass or reduced efficiency (which the authors combine here as "effective muscle mass") or because of reduced ...

The purpose of this investigation was to determine whether negative phosphate balance, which is developed during hypokinesia (a decreased number of walking steps/d) could be reversed with daily supplementation with phosphate, fluid, and salt (FSS). The studies on hypokinesia (HK) were performed for 364 d on 30 endurance-trained male volunteers ...

System linearity was assessed for exercise induced changes in energetics of forearm exercise. 31P-NMR spectroscopy techniques, with 12.5-s serial measurements of [PCr], [Pi], [ATP], and [H+] were employed during exercise and recovery transitions in four untrained men for moderate (1.7 W) and heavy (3.6 W) exercise. Signal averaging was applied ...

OBJECTIVE: Clinical and animal studies show increased acidification of skeletal muscle during exercise in heart failure, implying increased anaerobic metabolism, and impaired recovery from exercise, implying defective oxidative function. This study aimed to define the quantitative relationship between these changes in exercise and recovery and relate skeletal muscle bioenergetics to ...

The pathogenesis of morbidity associated with hyponatremia is postulated to be determined by the state of intracellular cerebral osmolytes. Previously inaccessible, these metabolites can now be quantitated by proton magnetic resonance spectroscopy. An in vivo quantitative assay of osmolytes was performed in 12 chronic hyponatremic patients (mean serum sodium 120 ...

Deficiencies of mitochondrial enzymes cause a number of severe neurologic syndromes in pediatric patients. Isolated myopathy secondary to enzymatic deficiency only rarely has been recognized and reported in adults. Three normal-appearing patients with unexplained dyspnea on exertion, tachycardia, and fatigue were studied with progressive incremental and constant load exercise testing ...

1. The recovery of power output and muscle metabolites was examined following maximal sprint cycling exercise. Fourteen male subjects performed two 30 s cycle ergometer sprints separated by 1.5, 3 and 6 min of recovery, on three separate occasions. On a fourth occasion eight of the subjects performed only one ...

In the collaborative exercise GEDNAP IV one EDTA blood sample (2 ml) and 5 bloodstains (0.5 ml on cotton) were investigated and in GEDNAP V, a total of 8 bloodstains (0.5 ml on cotton), including 2 mixed bloodstains. DNA typing was carried out using the RFLP systems YNH24/Hinf I and ...

We examined the effect of differences in exercise intensity on the time constant (tc) of phosphocreatine (PCr) resynthesis after exercise and the relationships between tc and maximal oxygen uptake (VO2max) in endurance-trained runners (n = 5) and untrained controls (n = 7) (average VO2max = 66.2 and 52.0 ml.min-1.kg-1, respectively). ...

Previous studies have shown considerable variability in the metabolic response of human skeletal muscle during a standardized exercise protocol. The goal of these studies was to investigate the factors responsible for the broad range of metabolic changes produced by fatiguing exercise. Experiments were performed to quantitate the measurement error of ...

Very little has been reported on muscle energetics during exercise in adolescents. This is attributable to the difficulty of subjecting children to muscle biopsy. The purpose of this study was to investigate the characteristics of muscle metabolism during exercise in vivo in adolescents by comparing firstly, with adults and secondly, ...

The aim of this study was to compare proton T2 and apparent diffusion coefficient (ADC) variations induced by exercise in skeletal muscle, to provide some more information on the source of their variations. T2 and ADC were measured in the forearm flexor digitorum muscles in 12 healthy volunteers at rest ...

The masseter muscles of six nonbruxing subjects (five men, one woman) and six bruxing subjects (four men, two women) were assessed during chewing by nuclear magnetic resonance spectroscopy (31P-NMR). The NMR spectra were collected on a GE Sigma 1.5T whole body magnet with a double-tuned 31P/1H surface coil. Two-minute trials ...