The effect of fatigue on the binding of glycolytic enzymes in the isolated gastrocnemius of Rana pipiens

Fatigue of isolated gastrocnemius muscles from R. pipiens leads to a marked increase in the proportion of phosphofructokinase bound to the particulate fraction and a decrease in the binding of lactate dehydrogenase, pyruvate kinase, creatine phosphokinase and glyceraldehyde-3-phosphate dehydrogenase. Only the proportion of aldolase bound to the particulate fraction was unaffected by fatigue. This pattern was unchanged when fatigued muscles were extracted at pH 6.5 rather than 7.5. Thus, muscle fatigue leads to opposite changes in the binding of the glycolytic enzymes.     

Nerve stimulation decreases malonyl-CoA in skeletal muscle.

This study was designed to determine the effect of in situ electrical stimulation of the sciatic nerve on malonyl-CoA, an inhibitor of carnitine palmitoyl transferase, in the gastrocnemius/plantaris muscle group of rats. The left sciatic nerve was stimulated at a frequency of 5 Hz with 100-ms trains of impulses (50 Hz) for 1, 3, or 5 min. At the end of stimulation, the left and right (nonstimulated) gastrocnemius/plantaris muscle groups were clamp-frozen and later analyzed for malonyl-CoA and other metabolites. No change was observed in the noncontracting contralateral muscles in malonyl-CoA, ATP, creatine phosphate (CP), or citrate. In the stimulated muscles, malonyl-CoA decreased from 1.7 +/- 0.1 to 1.0 +/- 0.1 nmol/g (P less than 0.05), and CP decreased from 15.8 +/- 0.9 to 12.2 +/- 1.0 mumol/g (P less than 0.05) after 3 min of stimulation. After 5 min of stimulation, malonyl-CoA was 1.0 +/- 0.1 nmol/g and CP was 10.3 +/- 1.3 mumol/g. When muscles were stimulated for 5 min with single impulses (5 Hz), malonyl-CoA was decreased from 1.8 +/- 0.3 to 1.0 +/- 0.1 nmol/g, with no change in CP, ATP, or adenosine 3',5'-cyclic monophosphate. Thus a decline in malonyl-CoA can be induced by muscle contraction independently of humoral influence.     

Comparative enzymology of AMP deaminase,adenylate kinase,and creatine kinase in vertebrate heart and skeletal muscle: the characteristic AMP deaminase levels of skeletal versus cardiac muscle are reversed in the North American toad

The specific activity of three characteristic enzymes, adenylate deaminase, adenylate kinase, and creatine kinase, in the skeletal muscles and heart of a variety of vertebrate land animals, including the human, are surveyed. Data from this study and available studies in the literature suggest that adenosine monophosphate deaminase in land vertebrates is quite high in white skeletal muscle, usually somewhat lower in red muscle, and 15-to 500-fold lower in cardiac muscle. Adenosine monophosphate deaminase is active primarily under ischemic or hypoxic conditions which occur frequently in white muscle, only occasionally in red muscle, and ought never occur in heart muscle, and this may therefore account for observed enzyme levels. The common North American toad, Bufo americanus, provides a striking exception to the rule with cardiac adenosine monophosphate deaminase as high as in mammalian skeletal muscle, whereas its skeletal muscle level of adenosine monophosphate deaminase is several times lower. The exceptional levels in the toad are not due to a change in substrate binding and are not accompanied by comparable change in the level of adenylate or creatine kinase. Nor do they signal any major change in isozyme composition, since a human muscle adenosine monophosphate deaminase-specific antiserum reacts with toad muscle adenosine monophosphate deaminase, but not with toad heart adenosine monophosphate deaminase. They do not represent any general anuran evolutionary strategy, since the bullfrog (Rana catesbeiana) and the giant tropic toad (Bufo marinus) have the usual vertebrate pattern of adenosine monophosphate deaminase distribution. Lower skeletal muscle activities in anurans may simply represent the contribution of tonic muscle fiber bundles containing low levels of adenosine monophosphate deaminase, but the explanation for the extremely high adenosine monophosphate deaminase levels in heart ventricular muscle is not apparent.Abbreviations AK adenylate kinase - AMP adenosine monophosphate - AMPD, AMP deaminase - CPK creatine (phospho)kinase - EHNA erythro-9-(2-hydroxy-3-nonyl)-adenine-HCl     

Kinetics of creatine phosphokinase and adenylate kinase. A two-dimensional NMR analysis

The kinetics of creatine phosphokinase and adenylate kinase catalyzed reactions were studied at equilibrium by two-dimensional Fourier transform phosphorus-31 nuclear magnetic resonance. For the creatine phosphokinase reaction, a pseudo-first-order rate constant of 0.29 s-1 was determined for the transfer of a phosphate group from adenosine triphosphate to creatine phosphate. For the adenylate kinase reaction two slow rate processes were required to describe the experimental results. The conversion of adenosine diphosphate to adenosine monophosphate was found to have a pseudo-first-order rate constant of 1.2 s-1, whereas that for the release of adenosine triphosphate from its enzyme complex occurred at a rate of 14 s-1.     

The foetal development of lactate dehydrogenase isoenzymes, glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase from human striated muscle

1. Human foetal skeletal muscles involved in support and in periodic contractility were studied for their content of total extractable lactate dehydrogenase, glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities as well as for the relative distribution of lactate dehydrogenase isoenzymes. 2. During foetal development a linear steady increase in total lactate dehydrogenase activity as well as a linear decrease in the H/M sub-unit ratio of the isoenzymes was found. 3. No significant changes were found in the activities of the enzymes of the hexose monophosphate shunt (C-6 oxidation). 4. The changes found suggest a steady increased synthesis of lactate dehydrogenase M-sub-units in human skeletal muscles during foetal development. 5. The weekly changes in the total lactate dehydrogenase activity and in lactate dehydrogenase isoenzymes are lower in muscles involved in support than in those involved in periodic contractility. 6. These findings, together with the literature available, are consistent with the morphological fact that foetal development of skeletal muscles mostly concerns the white muscle fibres and not the red muscle fibres.     

Relative effects of glycogen depletion and previous exercise on muscle force and endurance capacity

Endurance capacity of human vastus lateralis muscles was observed 24 h after hard exercise followed by either a carbohydrate-restricted or a carbohydrate-loaded diet (depletion and repletion conditions). In a control condition the subjects did no previous exercise and ate their normal diet. Each of these conditions was followed by an experimental protocol in which the five male subjects made a series of alternating 25-s static contractions of each leg at 50% maximal voluntary contraction until one leg failed to achieve the required force (Tlim). Glycogen concentration before the experimental protocol in both legs was significantly lower in the depletion than in the repletion condition. Muscle lactate and creatine phosphate concentrations were within normal limits before the static contractions. The number of contractions the repleted (12.7 +/- 2.2) and depleted (10.3 +/- 1.5) legs could sustain before Tlim were not different from each other, but both were 35% (P less than 0.05) fewer than the control (17.6 +/- 3.0). Surface electromyogram (EMG) amplitude was higher in depleted than in repleted or control muscles. At Tlim, EMG amplitude was maximal, creatine phosphate was 50-70% depleted, and lactate increased fourfold. Average glycogen utilization per contraction in both the repletion and depletion conditions was 5.8 mmol/kg dry wt, but postexercise lactate concentrations were lower in depleted (14.4 +/- 3.6 mmol/kg dry wt) than in repleted (43.2 +/- 7.4) muscles. The EMG frequency distribution shifted downward in all conditions during the experimental protocol and was independent of muscle lactate concentration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Free gracilis muscle transplantation, with microneurovascular anastomoses for the treatment of facial paralysis. A preliminary report.

A clinical operative technique for free muscle transplantation by microneurovascular anastomoses is presented. Two cases of free transfer of the gracilis muscle for dynamic reconstruction of facial paralysis are described, including a follow-up study with electromyography, light microscopy, and electron microscopy. We feel this new technique will have a wide range of application in reconstructive surgery.     

Muscle metabolism during prolonged exercise in humans: influence of carbohydrate availability.

Eight endurance-trained men cycled to volitional exhaustion at 69 +/- 1% peak oxygen uptake on two occasions to examine the effect of carbohydrate supplementation during exercise on muscle energy metabolism. Subjects ingested an 8% carbohydrate solution (CHO trial) or a sweet placebo (Con trial) in a double-blind, randomized order, with vastus lateralis muscle biopsies (n = 7) obtained before and immediately after exercise. No differences in oxygen uptake, heart rate, or respiratory exchange ratio during exercise were observed between the trials. Exercise time to exhaustion was increased by approximately 30% when carbohydrate was ingested [199 +/- 21 vs. 152 +/- 9 (SE) min, P < 0.05]. Plasma glucose and insulin levels during exercise were higher and plasma free fatty acids lower in the CHO trial. No differences between trials were observed in the decreases in muscle glycogen and phosphocreatine or the increases in muscle lactate due to exercise. Muscle ATP levels were not altered by exercise in either trial. There was a small but significant increase in muscle inosine monophosphate levels at the point of exhaustion in both trials, and despite the subjects in CHO trial cycling 47 min longer, their muscle inosine monophosphate level was significantly lower than in the Con trial (CHO: 0.16 +/- 0.08, Con: 0.23 +/- 0.09 mmol/kg dry muscle). These data suggest that carbohydrate ingestion may increase endurance capacity, at least in part, by improving muscle energy balance.     

Experimental free-muscle transplantation with microneurovascular anastomoses

In 13 rabbits the rectus femoris muscle was freely transplanted from the left to the right side using microneurovascular anastomoses. About 7 months after surgery the muscle transplants were assessed functionally by force measurements. On the average, the transplanted muscles regained 55 percent of the maximal tetanic tension of unoperated, normal rectus femoris muscles, expressed as force per gram of muscle weight even 68 percent. After functional assessment, the muscles were weighed and then used for histologic, histochemical, planimetric, and biochemical evaluation. H&E-stained cross sections showed a high content of healthy muscle fibers; only some small atrophic and single fat cells were scattered over the cross sections. Good reinnervation over the sutured muscle nerve was confirmed by the type-grouping of muscle fibers in the NADH and myofibrillar ATPase staining. There was an excellent correlation between the functional results and the histologic picture as well as the content of choline acetyltransferase (CAT). A certain parallelism was found between the function of the transplants and the content of hexokinase, but none for the other estimated muscle enzymes, such as malate dehydrogenase (MDH), creatine kinase (CK), and lactic dehydrogenase (LDH). All enzyme levels were lower than in normal muscles. The results of this experimental series underline the utility of muscle transplantation with microneurovascular anastomoses to restore lost muscle function, even in the extremities, when strong forces are needed.     

Fiber type and metabolic characteristics of lion (Panthera leo), caracal (Caracal caracal) and human skeletal muscle

Lion (Panthera leo) and caracal (Caracal caracal) skeletal muscle samples from Vastus lateralis, Longissimus dorsi and Gluteus medius were analyzed for fiber type and citrate synthase (CS; EC 2.3.3.1), 3-hydroxyacyl Co A dehydrogenase (3HAD; EC 1.1.1.35), phosphofructokinase-1 (PFK; EC 2.7.1.11), creatine kinase (CK; EC 2.7.3.2), phosphorylase (PHOS; EC 2.4.1.1) and lactate dehydrogenase (LDH; EC 1.1.1.27) activities and compared to human runners, the latter also serving as validation of methodology. Both felids had predominantly type IIx fibers (range 50-80%), whereas human muscle had more types I and IIa. Oxidative capacity of both felids (CS: 5-9 μmol/min/g ww and 3HAD: 1.4-2.6 μmol/min/g ww) was lower than humans, whereas the glycolytic capacity was elevated. LDH activity of caracal (346 ± 81) was higher than lion (227 ± 62 μmol/min/g ww), with human being the lowest (55 ± 17). CK and PHOS activities were also higher in caracal and lion compared to human, but PFK was lower in both felid species. The current data and past research are illustrated graphically showing a strong relationship between type II fibers and sprinting ability in various species. These data on caracal and lion muscles confirm their sprinting behavior.     

Purine accumulation in human fat cell suspensions. Evidence that human adipocytes release inosine and hypoxanthine rather than adenosine

Human adipocytes are of limited viability (7 +/- 2% release of lactate dehydrogenase/h) and contain active ectophosphatases which are capable of sequentially degrading ATP to adenosine. At densities of 30,000-40,000 cells/ml, human fat cell suspensions accumulated adenosine, inosine, and hypoxanthine, and their concentrations were 38 +/- 8, 120 +/- 10, and 31 +/- 7 nmol/liter after 3 h of incubation. Dipyridamole (10 mumol/liter), an inhibitor of nucleoside transport, caused a 5-7-fold increase in adenosine accumulation which was reduced by 85% on inhibition of ectophosphatases by beta-glycerophosphate and antibodies against ecto-5'-nucleotidase or alpha, beta-methylene 5'-adenosine diphosphate (10 mumol/liter), respectively, indicating that most of the adenosine is produced in the extracellular compartment. Accordingly, the spontaneous accumulation of adenosine was reduced beyond 5 nmol/liter on inhibition of ectophosphatase activities or removal of extracellular AMP by AMP deaminase (4 units/ml). Added adenosine (30 nmol/liter) disappeared until its concentration approached 5 nmol/liter. Isoproterenol (1 mumol/liter) had no effect on adenosine accumulation regardless whether purine production from extracellular sources was minimized or not. In contrast to adenosine, the concentrations of inosine and hypoxanthine displayed only a modest decrease (30-50%) on inhibition of ectophosphatase activities. In addition, isoproterenol caused a 2-3-fold increase in inosine and hypoxanthine production which was concentration-dependent and could be inhibited by propranolol. It is concluded that the adenosine that accumulates in human adipocyte suspensions is almost exclusively derived from adenine nucleotides which are released by leaking cells. By contrast, inosine and hypoxanthine are produced inside the cells, and the release of these latter purines appears to be linked to ATP turnover via adenylate cyclase.     

A murine skeletal muscle ischemia-reperfusion injury model: differential pathology in BALB/c and DBA/2N mice

Ischemia-reperfusion injuries can occur with diseasessuch as myocardial infarction and stroke and during surgical procedures such as organ transplantation and correction of aorticaneurysms. We developed a murine model to mimic abdominalaortic aneurysm repair with cross-clamping of the aorta distal to therenal artery. After model development, we compared the normalcomplement BALB/c mouse with the C5-deficient DBA/2Nmouse. To assess quantitative differences, we measured neuromuscularfunction up to 72 h after ischemia with a subjective clinicalscoring system, as well as plasma chemistries, hematology, andhistopathology. There were significant increases inclinical scores and creatine phosphokinase, lactate dehydrogenase, andmuscle histopathology scores in BALB/c mice compared with those inDBA/2N mice and sham-surgery mice. Muscle histopathology scores of thecranial tibialis and quadriceps correlated well with clinical signs,creatine phosphokinase, and lactate dehydrogenase, and indicated thegreatest pathology in these muscle groups. We developed a murine modelof skeletal muscle ischemia-reperfusion injury that can utilizethe benefits of murine genetic and transgenic models to assesstherapeutic principles of this model. Additionally, we have shown asignificant reduction in clinical signs, plasma muscle enzymeconcentrations, and muscle pathology in the C5-deficient DBA/2N mousein this model.

     

Model for microneurovascular muscle transplantation in the dog

Previous studies have suggested that successful transplantation of skeletal muscle to replace previously lost function depends on the mass of the transplanted tissue. In the present experiment, the possibility that careful microneurovascular surgical technique substantially improves the chances of successful transplantation of large-sized muscle was tested using dog gracilis muscle averaging 75 gm in weight. Gracilis muscles were completely excised ipsilaterally and were implanted into their original location (orthotopic) by reattaching tendons of insertion and origin. In addition, neurorrhaphies of nerve stumps were performed along with repair of the vascular pedicle using microsurgery techniques. After approximately 1 year, orthotopic transplants weighed about 70 percent of contralateral sham-operated gracilis muscles. Although average tension output of transplants declined to about 60 percent of control values, three of the most successfully transplanted muscles produced between 73 and 88 percent of control force. A significant increase in the number of slow-twitch-oxidative fibers was correlated with a slight but significant reduction in the maximal velocity of shortening of transplanted muscles. The ability of transplants to resist fatigue when repetitively stimulated was similar to the endurance capacity of control muscles. These results suggest that microneurovascular surgery may enhance the more complete restoration of function of transplanted skeletal muscles of relatively large size.     

Effect of spinal cord stimulation on the metabolism of developing latissimus dorsii muscles in chick embryo

Influence of chronic spinal cord stimulation upon some characteristic enzyme activities of energy metabolism was investigated in slow anterior (ALD) and fast posterior (PLD) latissimus dorsii muscles of the chick embryo. During embryonic life, oxidative metabolism (as evaluated by the activity of malate dehydrogenase (MDH] represents the main energetic pathway in both slow and fast muscles. At the end of embryonic life, an increase in anaerobic (as evaluated by the activity of lactate dehydrogenase (LDH] and creatine phosphokinase (CPK) activities occurs in PLD muscle. Chronic spinal cord stimulation at a low frequency was performed from the 10th day to the 16th day of embryonic development. In ALD, the enzyme activities were unaffected, while in PLD a concomitant decrease in LDH and CPK activities was observed.     

In vivo glycolytic equilibria in dog gracilis muscle

While the equilibrium assumption and the validity of using total measured concentrations for near equilibrium indicator reactions have been widely tested in liver, these have not been systematically evaluated in skeletal muscle. Vascularly isolated dog gracilis muscles were stimulated via the nerve at 4 Hz, and tissue was sampled by quick freezing at rest and after 10, 15, 30, 60, and 180 s of stimulation or after stimulation in the presence of glycolytic blockade by iodoacetate. Phosphocreatine, creatine, and several glycolytic intermediates were measured in tissue extracts. The in vivo mass action ratios for triosephosphate isomerase and aldolase were evaluated relative to substrate concentrations and compared with equilibrium constants determined in vitro. Although there was evidence of substrate binding at low substrate levels for the triosephosphate isomerase reaction, the in vivo mass action ratios for both reactions stabilized at a constant value at moderate substrate levels and in glycolytically blocked muscles. It was concluded that both enzymes are in apparent equilibrium in vivo, but the equilibrium constants are lower than those determined in vitro. The mass action ratios of the combined creatine kinase, lactate dehydrogenase, glyceraldehyde-phosphate dehydrogenase and phosphoglycerate kinase reactions were determined for resting muscles. These reactions are also at equilibrium and the equilibrium constants are consistent with in vitro values.     

Muscle enzyme activities in a deep-sea squaloid shark, Centroscyllium fabricii, compared with its shallow-living relative, Squalus acanthias

The activities of several enzymes of energy metabolism were measured in the heart, red muscle, and white muscle of a deep and a shallow living squaloid shark, Centroscyllium fabricii and Squalus acanthias, respectively. The phylogenetic closeness of these species, combined with their active predatory nature, similar body form, and size makes them well matched for comparison. This is the first time such a comparison has been made involving a deep-sea elasmobranch. Enzyme activities were similar in the heart, but generally lower in the red muscle of C. fabricii. Paralleling the trend seen in deep-sea teleosts, the white muscle of C. fabricii had substantially lower activities of key glycolytic enzymes, pyruvate kinase and lactate dehydrogenase, relative to S. acanthias or other shallow living elasmobranchs. Unexpectedly, between the squaloid sharks examined, creatine phosphokinase activity was higher in all tissues of the deep living C. fabricii. Low white muscle glycolytic enzyme activities in the deep-sea species coupled with high creatine phosphokinase activity suggests that the capacity for short burst swimming is likely limited once creatine phosphate supplies have been exhausted.     

Effect of a short-term dietary creatine supplementation on high-energy phosphates in the rat myocardium.

The aim of this study was to find out whether creatine (Cr) feeding affects total creatine (TCr), phosphocreatine (PCr), adenine nucleotide contents and beta-hydroxy-acyl-CoA-dehydrogenase (HAD) activity in myocardium as compared to red skeletal muscle. Ten adult Wistar rats received Cr (2.5% of diet weight) for 7 days. In Cr fed rats, PCr was increased (by approx. 20%) in cardiac and in soleus muscles with ATP elevated in myocardium and TCr and free Cr in soleus. In both muscles, Cr feeding enhanced HAD activity. It is concluded, that dietary Cr does increase cardiac muscle high energy phosphate reserves and its oxidative potential.     

Role of creatine phosphokinase in cellular function and metabolism.

This paper summarizes the data concerning the role of the creatine phosphokinase system in muscle cells with main attention to the cardiac muscle. Creatine phosphokinase isoenzymes play a key role in the intracellular energy transport from mitochondria to myofibrils and other sites of energy utilization. Due to the existence of the creatine phosphate pathway for energy transport, intracellular creatine phosphate concentration is apparently an important regulatory factor for muscle contraction which influences the contractile force by determining the rate of regeneration of ATP directly available for myosin ATPase, and at the same time controls the activator calcium entry into the myoplasm across the surface membrane of the cells.     

The effects of temperature acclimation on the oxygen consumption and enzyme activity of red and white muscle fibres isolated from the tropical freshwater fish Oreochromis niloticus

The standard oxygen consumption rate and the activities of muscle citrate synthase, creatine phosphokinase and lactate dehydrogenase in the tropical fish Oreochromis niloticus acclimated to either 20.5 ± 0.3° C or 26.5 ± 0 ± 5 ± C for at least 3 months were investigated. The standard oxygen consumption rate of individual fish from the two acclimation temperatures was determined at 20, 25 and 30 ± C. At all experimental temperatures, the standard oxygen consumption rate of fish acclimated to 20.5 ± 0.3° C was significantly higher than that of fish kept at 26.5 ± 0.5 ± C. In both groups smaller individuals had a higher oxygen consumption rate than large ones.
Analyses of the activity levels of citrate synthase (CS), creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) in both red and white muscles isolated from fish kept under the two temperature regimes were performed at 26 ± C. The activity of CS in both red and white muscles isolated from the 20.5 ± 0.3° C acclimated fish was significantly higher than that of muscles isolated from the 26.5 ± 0.5 ± C acclimation group. Similarly, the CPK activity in white muscles isolated from fish acclimated to 20.5 ± 0.3 ± C was higher than that of muscles obtained from the 26.5 ± 0.5 ± C acclimation group. However, the CPK activity in red muscles isolated from the two fish groups was not significantly different. The opposite results were obtained for LDH activity. For example, the LDH activity of white muscles isolated from fish acclimated to 26.5 ± 0.5 ± C was significantly higher than that of the same muscles but from the 20.5 ± 0.3 ± C acclimated fish. No differences were observed in the LDH activity of red muscles isolated from the two fish groups.     

Enzymological studies on hereditary avian muscular dystrophy.

White and red muscles of normal and genetically dystrophic chickens were compared with regards to activity levels of three soluble enzymes, glyceraldehyde-3-phosphate dehydrogenase, creatine phosphokinase, and acetyl phosphatase. In dystrophic white muscle (pectoral), activity of the two sulfhydryl enzymes, glyceraldehyde-3-phosphate dehydrogenase and creatine phosphokinase, was preferentially lost from the sarcoplasm resulting in decreased specific activities. By contrast, acetyl phosphatase was preferentially retained and showed increased specific activity. Dystrophic white muscle had decreased sulfhydryl content in the soluble proteins, severe reduction in muscle mass, fatty infiltration, and fragmentation of fibers. Red dystrophic muscles (thigh) were minimally involved in accordance with the known sparing of red fibers. Enzyme activities were correlated with histological observations. The results suggested that the disease process in dystrophic white muscle may be related to alterations in the sulfhydryl groups of proteins. The data are correlated with the beneficial effects of our treatment of hereditary avian dystrophy with the sulfhydryl compound, penicillamine (Chou, T.H., Hill, E.J., Bartle, E., Woolley, K., LeQuire, V., Olson, W., Roelofs, R., and Park, J.H. (1975) J. Clin. Invest. 56, 842-849).