Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of chronic "steady-state" and high-speed interval running were investigated on time-course changes in certain biochemical properties of cardiac and skeletal muscle fiber types of rats. Nine weeks of the interval program resulted in significant increased (15%) in both cardiac enlargement and ATPase activity of myofibrils; whereas increases in these parameters were only transient and not significant at the termination of the program involving steady-state running. Neither program induced appreciable alterations in citrate synthase and phosphofructokinase activity in cardiac muscle. In fast-twitch white fibers, "steady-state" training induced only a transient 45% increase in citrate synthase activity in contrast to a progressive twofold change with interval training. Both programs resulted in similar increases (45-50%) in citrate synthase activity in fast-twitch and slow-twitch red fibers. However, the patterns of increase for both fiber types differed between the two programs. These findings suggest that training programs incorporating elements of both "steady-state" incline and high-speed interval running can potentially induce respiratory enzyme adaptations in the greatest spectrum of rodent skeletal muscle fibers in addition to inducing adaptations to enhance contractile potential in cardiac muscle.
 ...
PMID:Time course adaptations in cardiac and skeletal muscle to different running programs. 13 67

The effects of bilateral functional overload on enzyme changes in fast-twitch plantaris muscles were studied on different groups of rats: 1) normal-control; 2) normal-exercise; 3) overload-control; and 4) overload-exercise. Overload was accomplished by surgical elimination of synergists. Exercising groups walked up a 65% grade, 3 m/min, 2 h/day. Peak muscle enlargement of the overload groups was reached after 5 wk. Citrate synthase, phosphofructokinase, and myofibril ATPase activities were consistantly depressed by approximately 30%, 40%, and 18%, respectively, in overload as compared to normal groups. Daily exercise prevented the decrease in only citrate synthase activity. Unilateral overload of medial gastrocnemius muscle indicated that both fast-twitch oxidative-glycogenolytic and fast-twitch glycogenolytic fiber types undergo enzyme changes in response to the functional stress. However, changes in the former were in closer agreement with the net changes seen in the plantaris than the latter. Soleus muscle responded to overload primarily with marked reductions in respiratory capacity. These findings suggest that certain enzyme systems are altered with functional overload in different fiber types. However, the alterations in certain enzyme systems may, in part, be independent of the process of hypertrophy.
 ...
PMID:Effect of functional overload on enzyme levels in different types of skeletal muscle. 13 68

An extension of a previous model [2] is proposed of the glycolysis of erythrocytes which includes realistic rat laws for the hexokinase-phosphofructokinase system and for the 2,3-P2G phosphatase. Whereas most conclusions previously drawn are reinforced, the mechanism of ATP regulation is different in the present model. The ATP concentration is mainly regulated by the inhibitory action of ATP and the activating effect of AMP on the phosphofructokinase. The role of the 2,3-P2G bypass as a buffer of changes in the ATP demand is of lesser significance than previously thought. Besides the feedback action of the adenine nucleotides on the hexokinase-phosphofructokinase system in the quasisteady state the role of 2,3-P2G as an energy source is important since it can yield ATP for a certain period of time. The present version of the model describes qualitatively the experimental data on the modulation of Na+-K+-ATPase.
 ...
PMID:An extended model of the glycolysis in erythrocytes. 14 74

ATPase activity of actomyosin and activity of glycogenolytic enzymes were distinctly increased during postnatal period of development. Direct correlation was observed between the actomyosin ATPase and phosphofructokinase, phosphohexoisomerase, enolase, pyruvate kinase, lactate dehydrogenase and "bound" fraction of aldolase. Kinetic patterns of phosphofructokinase (Km and Hill's coefficient) were not altered at the postnatal period. Formation of complexes between the contractile proteins and glycolytic enzymes appears to be important in development of contractile function.
 ...
PMID:[Comparative study of the changes in the ATPase activity of actomyosin and in the activity of skeletal muscle glycolytic enzymes in the early postnatal period of development]. 14 21

It is not known whether cellular adaptations of the ventilatory muscles are induced by increased respiratory loads. A chronic respiratory load was produced in rats by tracheal banding. Five weeks after the imposition of this increased load, biochemical and histochemical analyses were performed on the diaphragm and intercostal muscles. The oxidative capacity, as indicated by succinate dehydrogenase (SDH) activity, increased 38% in the diaphragm. The capacity for beta-oxidation fatty acids, as indicated by 3-hydroxy-acyl-CoA dehydrogenase (HADH) activity, increased 29%. The glycolytic capacity, as indicated by phosphofructokinase (PFK) activity, did not change. Similar enzymatic adaptations were observed in the intercostal muscles. The proportion of slow-twitch muscle fibers, as indicated by the myofibrillar adenosine triphosphatase (ATPase) stain, increased in the diaphragm, but not in the intercostal muscles. Thus, these ventilatory muscles responded with an increase in their oxidative capacity, and the diaphragm reponded with an increase in the proportion of muscle fibers having the myofibriller ATPase staining characteristic of slow-twich fibers. We conclude that cellular adaptations are induced in the ventilatory muscles by chronic increased respiratory loads.
 ...
PMID:Cellular adaptations of the ventilatory muscles to a chronic increased respiratory load. 14 78

Progressive strength training was performed 3 times a week for 8 weeks by 14 male students (19-31 yrs.). The training program consisted mainly of dynamic exercises for the leg extensors with maximal or close to maximal loads. The training caused significant improvements in dynamic and isometric strength. One repetition maximum in squats increased with 67%, Sargent jump with 22%, and maximal voluntary isometric contraction (MVC) with 13%, respectively. Body weight and leg muscle circumferences remained unchanged after training, whereas total body potassium, lean body mass and calculated total muscle mass increased, suggesting a change in body composition with training. Muscle biopsies were obtained from vastus lateralis for fibre analyses and determination of enzyme activities. There were no changes in muscle fibre composition or fibre area with training. The activities of Mg2+ stimulated ATPase, creatine phosphokinase and phosphofructokinase remained unchanged, whereas myokinase activity was increased after training from (1.41 to 1.52 moles x 10(-4) x g-1 x min-1, p less than 0.05). After training significant correlations (p less than 0.01) were demonstrated between Mg2+ stimulated ATPase activity and % fast twitch fibres (% FT) (r = 0.67), as well as between myokinase activity and % FT (r = 0.86).
 ...
PMID:Effect of strength training on enzyme activities and fibre characteristics in human skeletal muscle. 17 78

Fibre-type classification of human skeletal muscle into type I and type II fibres is mostly based on their slight or strong staining with the myosin adenosine triphosphatase reaction. In order to evaluate the reliability of this screening technique a combined histochemical and biochemical study was performed on normal and diseased skeletal muscle of human subjects. In the present investigation activities of enzymes which play a role in the aerobic and anaerobic pathways and which can characterize fibre type, were examined in muscle specimens, with no apparent disease of the neuromuscular system. Special attention is given to the maximal activities of phosphofructokinase and fructose-1,6-diphosphatase, the rate limiting enzymes for the regulation of the glycolysis and glyconeogenesis, respectively. A most important feature of the biochemical findings is the constancy of the activity ratios of the examined enzymes. From these results and from the histochemical results it can be concluded that in apparently normal adult human skeletal muscle the ATP-ase technique for type I and type II typing is reliable. For fibres with an intermediate intensity of staining with the myosin ATPase technique of typing it is also necessary to apply other enzyme histochemical techniques.
 ...
PMID:The value of enzyme histochemical techniques in classifying fibre types of human skeletal muscle. 1. Adult skeletal muscles with no apparent disease of the neuromuscular system. 19 26

The effects of thyroid deficiency (Td) and of chemical sympathectomy (Sx) were studied on marker enzymes of energy metabolism in cardiac muscle of neonatal and of adult rats. Td prevented the normal development of neonatal body weight, relative heart mass, and cardiac levels of cytochrome c (-22%), citrate synthase (-27%), phosphofructokinase (-20%) and Mg2+- and Ca2+-ATPase activity of purified myofibrils (-33%, -44%). Exogenous thyroxin replacement restored those parameters studied to normal with the exception that it persistently elevated citrate synthase activity significantly above normal control levels. Responses similar to those of Td neonates occurred when adult rats were similarly treated. Sx produced no consistent effects on respiratory and glycogenolytic marker enzymes, but caused a 20% reduction in Ca2+-ATPase activity of both neonatal and adult cardiac myofibrils. These findings suggest that cardiac muscle cells require thyroxin for normal growth and enzyme development. Also, Sx may impair cardiac functional capacity by altering Ca2+ activity of actomyosin ATPase.
 ...
PMID:Effects of thyroid deficiency and sympathectomy on cardiac enzymes. 21 2

Brusatol, a quassinoid with potent antineoplastic activity against P-388 lymphocytic leukemia cell proliferation, significantly inhibited P-388 cell hexokinase, phosphofructokinase, malic dehydrogenase, and succinic dehydrogenase. Mitochondrial oxidative phosphorylation, basal, and adenosine diphosphate-stimulated respiration, utilizing succinate and alpha-ketoglutarate as the substrate, was suppressed significantly by in vivo treatment with brusatol. However, brusatol treatment had no effect on liver oxidative phosphorylation. Brusatol greatly increased P-388 cyclic AMP levels but had no effect on liver cyclic nucleotides. Similar inhibitory effects on P-388 cell oxidative phosphorylation were found in vitro with brusatol, bruceoside A, and bruceantin. Brusatol had no effect on adenosine triphosphatase activity or on uncoupling of oxidative phosphorylation. Rather, brusatol appeared to increase the concentration of reduced mitochondrial electron-transport cofactors, thereby blocking aerobic respiration. A proposed mechanism of action is discussed.
 ...
PMID:Antitumor agents. XXXV: Effects of brusatol, bruceoside A, and bruceantin on P-388 lymphocytic leukemia cell respiration. 22 89

Muscle biopsy samples were obtained from healthy subjects in order to evaluate quantitative differences in single fibres of substrate (glycogen and triglyceride) and ion concentrations (Na+ and K+) as well as enzyme activity levels (succinate-dehydrogenase, SDH; phosphofructokinase, PFK; 3-hydroxyacyl-CoA-dehydrogenase, HAD; myosin ATPase) between human skeletal muscle fibre types. After freeze drying of the muscle specimen fragments of single fibres were dissected out and stained for myofibrillar-ATPase with preincubations at pH's of 10.3, 4.6, 4.35. Type I ("red") and II A,B, and C ("white") fibres could then be identified. Glycogen content was the same in different fibres, whereas triglyceride content was highest in Type I fibres (2-3 X Type II). No significant differences were observed for Na+ and K+ between fibre types. The activity for the enzymes studied were quite different in the fibre types (SDH and HAD, Type I is approximately 1.5 X Type II; PFK Type I is approximately 0.5 X Type II, Myosin ATPase Type I is approxiamtely 0.4 X Type II). The subgroups of Type II fibres were distinguished by differences in both SDH and PFK activities (SDH, Type II C is greater than A is greater than B; PFK, Type II B is greater than A is approximately C). It is concluded that contractile and metabolic characteristics of human skeletal fibres are very similar to many other species. One difference, however, appears to be than no Type II fibres have an oxidative potential higher than Type I fibres.
 ...
PMID:Metabolic characteristics of fibre types in human skeletal muscle. 24 87


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>