Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.4.1 (myosin ATPase)
 1,140 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We measured the interrelationships between ventricular muscle myosin mass, myosin ATPase activity and collagen in cats with varying degrees of hypertrophy from left ventricular (LV) pressure-overload produced by either aortic banding or renal hypertension. In order to compare two models of LV pressure-overload with different time courses of progression, the results were analyzed as a function of LV mass or LV weight/body weight (LV/BW) ratio. Myosin was quantitated by SDS-polyacrylamide gel electrophoresis and hydroxyproline was measured as an index of collagen. Myosin concentration was positively correlated with increasing LV mass in control cats. However, in pressure-overloaded LV, myosin concentration was elevated and nearly constant for LV less than 9.0 g, but decreased in LV greater than 9.0 g. Myosin concentration in pressure-overloaded LV was greatest before a significant increase in LV/BW ratio. Hydroxyproline concentration was inversely related to myosin concentration in both LV pressure-overload models and increased with the severity of hypertrophy. Actomyosin ATPase activity in pressure-overloaded LV, was not significantly different from control over a wide range of LV/BW ratios. However, absolute myosin ATP hydrolysis in pressure-overloaded LV, increased by as much as 40%, relative to control, due primarily to increased myosin. The changing spectrum and interrelationships of myosin and collagen were independent of the mechanism of pressure-overload, but were correlated with the severity of hypertrophy.
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PMID:Myocardial changes during the progression of left ventricular pressure-overload by renal hypertension or aortic constriction: myosin, myosin ATPase and collagen. 295 26

To determine whether the relative decline in cardiac myosin isoenzyme V1 with maturation continues progressively into senescence and whether thyroxine could reverse age-associated changes in the myosin isoenzyme profile and contraction, rats 2, 8, and 24 months old were treated with thyroxine, 6.4 mg/kg, for 7 days. Myosin isoenzymes, Ca2+-myosin ATPase activities, and isometric contractile function were measured in cardiac preparations from thyroxine-treated animals and age-matched controls. Right ventricular hypertrophy did not occur with aging in controls. Thyroxine increased right ventricular weight in each age group compared to the control group. Body weight decreased by 10% in all thyroxine-treated rats. The relative right ventricular V1 isoenzyme content progressively decreased from 75 +/- 1% to 54 +/- 1% and 14 +/- 1% in controls at 2, 8, and 24 months, respectively, and was associated with a reciprocal increase in V3 myosin isoenzyme. Ca2+-myosin ATPase activity also progressively declined monotonically with age in the control rats from 854 +/- 28 nmol Pi/mg prot/min at 2 months to 529 +/- 28 nmol Pi/mg prot/min at 24 months. Thyroxine administration increased right ventricular V1 at each age to 97 +/- 2%, 73 +/- 2%, and 59 +/- 2% at 2, 8, and 24 months, respectively. A thyroxine induced increase in the Ca2+-myosin ATPase activity could be detected only in the 24-month-old animals.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Changes in myosin isoenzymes, ATPase activity, and contraction duration in rat cardiac muscle with aging can be modulated by thyroxine. 295 64

When 1 mM ATP is added to human dermal fibroblasts (DF) in monolayer culture permeabilized by glycerol, they undergo a rapid reduction in length and their intracellular actin filaments aggregate. This process is referred to as cell contraction. Treating glycerol-permeabilized DF with alkaline phosphatase before adding 1 mM ATP should cause dephosphorylation. Dephosphorylated preparations do not undergo cell contraction initiated by ATP. When myosin light-chain kinase (MLCK) isolated from turkey gizzard is added with cofactors to cells dephosphorylated by alkaline phosphatase treatment, contraction is restored. DF incubated for 24 h with db cAMP or cholera toxin show elevated intracellular concentrations of cAMP and little cell contraction. Contraction is reestablished when MLCK with cofactors is incubated with these preparations before ATP is added. Fibroblasts from Epidermolysis Bullosa dystrophica recessive patients produce excess cAMP. Those cells show minimal contraction, however; treating them with MLCK and cofactors renews contraction brought about by ATP. When DF are incubated with trifluoperazine to block calmodulin-dependent enzyme reactions, cell contraction is inhibited. Adding cytochalasin B disrupts microfilaments and also inhibits contraction. This work supports the idea that myosin ATPase is critical to cell contraction. Myosin ATPase is dependent on the phosphorylation of the regulatory peptide, myosin light chain. Elevating intracellular concentrations of cAMP or treatment of permeabilized cell preparations with alkaline phosphatase may inhibit myosin ATPase activity. The restoration of phosphorylation by adding MLCK with cofactors served to reestablish cell contraction.
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PMID:ATP-induced cell contraction in dermal fibroblasts: effects of cAMP and myosin light-chain kinase. 301 87

Types 1 and 2C fibers in human skeletal muscle were cross-reactively identified with monoclonal anti-bovine neurofilament (200 kd) antibody. Thirty seven biopsy samples including sixteen vastus lateralis muscles, twelve lumbar paravertebral muscles, six gluteus medius muscles, two flexor carpi ulnaris muscles, and one flexor pollicis longus muscle, were examined. Serial transverse sections were stained histochemically with myofibrillar ATPase (pH 10.4, 4.6, 4.3) and DPNH-tetrazolium reductase reactions, and immunochemically using the avidin-biotin-peroxidase complex with the primary antibodies of monoclonal anti-bovine neurofilament (200 kd, 160 kd, 70 kd) antibodies and anti-bovine glial filament acidic protein antibody. The immunochemical reaction with anti-NF (200 kd) antibody could distinguish two kinds of fibers; positive and negative in all of the specimens. No fiber was recognized with other antibodies. Myosin ATPase reactions in serial sections proved that the positively stained fibers with anti-NF (200 kd) antibody were types 1 and 2C fibers and negative fibers types 2A and 2B fibers. At present, it is not known what substance is responsible for the cross-reaction with the monoclonal anti-NF (200 kd) antibody in types 1 and 2C fibers, but this unique antibody would be valuable in two aspects: one concerns the problem of the evolution of fiber types, and the other the utility as another supplemental method to conventional myosin ATPase scheme.
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PMID:Cross reactive identification of types 1 and 2C fibers in human skeletal muscles with monoclonal anti-neurofilament (200 kd) antibody. 311 44

The goal was to describe the metabolic profile of ganglionic and cortical arteries and arterioles in aging normotensive male rats. Five enzymes indicative of key metabolic pathways in the vessel walls were semiquantitatively evaluated using bright-field histochemical microscopy. Lactate dehydrogenase showed significant reactivity which increased with vessel diameter in cortical and ganglionic vessels in all age groups tested. Succinate dehydrogenase and cytochrome oxidase showed little reactivity in both cortical and ganglionic vessels, suggesting a reduced role for aerobic metabolic pathways. Myosin ATPase reactivity was high in cortical and ganglionic vessels. Only this enzyme showed an increased reactivity that was correlated with the age and diameter of the vessel. Glucose-6-phosphate dehydrogenase reactivity was more pronounced in cortical than ganglionic vessels, suggesting that the hexose-monophosphate-shunt may be more active in the cortical vessels. There were no regional differences in enzyme reactivity throughout the caudatoputamen. In conclusion, both the cortical and ganglionic vessels are metabolically active, with significant anaerobic glycolysis, and reduced, but observable capacity for aerobic metabolism. The decreased myosin ATPase reactivity and the low level of glucose-6-phosphate dehydrogenase reactivity in the ganglionic arterioles of senescent rats may contribute to the susceptibility of these vessels to cerebrovascular accidents.
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PMID:A histochemical study of cerebral cortical vessels and ganglionic vessels of the caudatoputamen in aging normotensive rats. 315 35

Uniformly 32P-labeled polyribonucleotides of high specific activity can be rapidly and easily synthesized from commercially available ribonucleoside 5'-[alpha-32P]triphosphates by using two enzymes in sequence. Myosin ATPase completely and irreversibly converted any triphosphates to diphosphates in 10 min. The product diphosphates, without purification, can be polymerized by polynucleotide phosphorylase (PNPase) in 1 h with an average yield of 60%. By choosing the desired molar ratio of radioactive and nonradioactive tri- or diphosphates, polymers of a wide range of specific activity can be obtained. Since myosin ATPase and PNPase both have little base specificity, the method can be used to synthesize a radiolabeled polymer of any desired base composition.
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PMID:Enzymatic synthesis of uniformly 32P-labeled polyribonucleotides and high-specific-activity ribonucleoside 5'-[alpha-32P]diphosphates. 315 30

Previous studies have shown that in rats diabetes mellitus leads to a decrease in cardiac ventricle myosin V1 and an increase in myosin V3 levels. Insulin administration reverts myosin isoenzyme distribution to normal levels. It is currently unclear whether the effects of insulin on myosin isoenzyme distribution are a direct effect of the hormone or are mediated through insulin-induced alterations in cardiac metabolism. To gain further insight into this question diabetic rats received methyl palmoxirate, a potent inhibitor of long-chain fatty acid oxidation. Administration of 25 mg methyl palmoxirate X kg body wt-1 X day-1 to diabetic rats for 4 wk leads to a partial reversal of the effects of diabetes. Myosin V1 predominance is re-established and Ca2+-activated myosin ATPase activity increases by 60% (Ca2+-myosin ATPase normal rats 1.067 +/- 0.13 mumol Pi X mg protein-1 X min-1, diabetic rats 0.609 +/- 0.05 mumol Pi X mg protein-1 X min-1, diabetic + methyl palmoxirate rats 0.912 +/- 0.06 mumol Pi X mg protein-1 X min-1). The methyl palmoxirate-induced increase in myosin V1 levels and Ca2+-activated myosin ATPase activity occurred in the absence of changes in insulin and thyroid hormone levels. Methyl palmoxirate may have acted through its known inhibitory effect on cardiac beta-oxidation and/or the resultant stimulatory effect on glycolytic flux. Our findings may indicate that changes in cardiac substrate consumption can influence myosin isoenzyme predominance.
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PMID:Methyl palmoxirate increases Ca2+-myosin ATPase activity and changes myosin isoenzyme distribution in the diabetic rat heart. 315 15

Myosin was isolated from mouse, rat, rabbit, pig and bovine atrial and ventricular myocardium and Ca2+-ATPase activity was examined. In the mouse the ATPase activity of myosin was the same in atrial and ventricular myocardium. In larger animal species, the activity of atrial myosin ATPase was higher than that of ventricular myocardium and the larger the animal species the greater the divergence between the activities of atrial and ventricular myosin ATPase. The relevance of these observations to regulation of heart contractility is discussed.
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PMID:Atrial and ventricular myosin ATPase--divergence with increasing animal species size. 316 7

An assay specific for myosin ATPase in whole-cell extracts of cultured heart cells has been developed. Myosin ATPase is measured by the production of Pi from ATP in the presence of high ionic strength (0.5 M KCl) at pH 9.1. Enzyme activity is maximal with 10 mM CaCl2 and completely inhibited with 5 mM MgCl2. Spontaneously beating myocytes grown in the presence of 10% newborn calf serum and 0.1 mM 5-bromo-2'-deoxyuridine show a significant rise in myosin ATPase between Days 1 and 4 in culture. The measurement of myosin ATPase allows for the quantitation of cellular myosin content, and can be used to assess changes in myosin content that occur during growth, development, and cellular repair.
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PMID:Measurement of myosin adenosinetriphosphatase and myosin content in cultured heart cells. 316 Mar 6

This study utilized electron microscopy and enzyme histochemistry to examine the morphological steps associated with the formation of a lumen in the end-buds of the embryonic rat submandibular gland. Lumen formation involved the development of junctional complexes by the central cells of the end-buds late on the 16th day of gestation. These junctional complexes established the apical domains of the presecretory cells, and cytofilament aggregates were observed beneath the presumptive luminal plasma membranes. This central area of the end-buds showed strong myosin ATPase activity, presumably associated with the cytofilaments. On the 17th day of gestation, small lumina appeared at the sites delineated by the junctional complexes. The myosin ATPase activity appeared to surround the newly opened lumina. By the 18th day of gestation, microvilli were seen projecting into the lumina, and secretory granules were often visible in the apical cytoplasm near the luminal plasma membranes of the early secretory cells. Myosin ATPase activity was greatly reduced once the lumina had formed.
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PMID:Lumen formation during development of the rat submandibular gland. 347 54


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