Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.3.1 (Mg2+-ATPase)
 1,484 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transverse tubule (TT) membrane vesicles have been isolated from the skeletal muscle of normal and malignant hyperthermia-susceptible (MHS) pigs. MHS and normal TT did not differ in the distribution of the major proteins, cholesterol, or phospholipid content, (Na+ + K+)-ATPase activity, [3H]ouabain binding, Ca2+-ATPase activity, Mg2+-ATPase activity, or [3H]saxitoxin binding. Furthermore, in the presence of micromolar Ca2+, MHS and normal TT did not differ significantly in the KD values for either [3H]nitrendipine binding (2.7 +/- 0.6 and 3.3 +/- 0.5 nM, respectively) or (-)-[3H]desmethoxyverapamil ([3H]D888) binding (7.2 +/- 0.9 and 6.4 +/- 0.6 nM, respectively). However, in contrast to normal TT, MHS TT exhibited a significantly decreased Bmax for both [3H]nitrendipine binding (26.4 +/- 5.4 for MHS versus 40.6 +/- 3.7 pmol/mg protein for normal TT) and [3H]D888 binding (17.8 +/- 7.0 for MHS versus 37.4 +/- 5.9 pmol/mg protein for normal TT). At calcium concentrations greater than 0.1 mM, there was a greater inhibition of [3H]nitrendipine binding to normal than to MHS TT such that binding was now similar for both preparations. As with purified TT, [3H]nitrendipine binding to MHS muscle homogenates was significantly less than to normal muscle homogenates (109 +/- 20 versus 211 +/- 19 fmol/mg protein, for MHS and normal TT, respectively); this difference was not apparent when 100 mM CaCl2 was included in the binding medium. We conclude that the altered MHS TT dihydropyridine receptor properties may reflect an adaptation of the TT voltage sensing mechanism to the abnormal sarcoplasmic reticulum calcium release channel regulation in MHS muscle.
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PMID:Altered transverse tubule dihydropyridine receptor binding in malignant hyperthermia. 253 21

To investigate possible abnormalities in erythrocyte membrane enzyme activities in the pharmacogenetic disorder MH, membrane ATPase activities have been examined in erythrocyte ghosts prepared from red blood cells of MHS and normal swine. While no differences were noted in Mg2+-ATPase activities, the (Na+, K+)-ATPase activity of MHS erythrocyte ghosts was less than that of normal ghosts. Ca2+-ATPase activity exhibited low- and high-affinity Ca2+-binding sites in both types of erythrocyte ghost. While the Km for Ca2+ was greater for normal than for MHS erythrocyte ghosts at the high-affinity Ca2+-binding site, the reverse was true at the low-affinity Ca2+-binding site. Irrespective of the type of calcium binding site occupied, the Vmax for normal erythrocyte ghost Ca2+-ATPase activity was greater than that for MHS ghosts. In the presence of calmodulin, there was now no difference between MHS and normal erythrocyte ghosts in either the Km for Ca2+ or the Vmax of the Ca2+-ATPase activity. To determine if the calcium pumping activity of intact MHS and normal pig erythrocytes differed, calcium efflux from the 45Ca-loaded erythrocytes was determined; this activity was significantly greater for MHS than for normal erythrocytes. Thus, the present study confirms that there are abnormalities in the membranes of MHS pig red blood cells. However, we conclude that these abnormalities are unlikely to result in an impaired ability of MHS erythrocytes to regulate their cytosolic Ca2+ concentration.
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PMID:Erythrocyte membrane ATPase and calcium pumping activities in porcine malignant hyperthermia. 296 54

The activity of enzymes transporting calcium across the membrane of the muscle fibre and sarcoplasmic reticulum was studied. The activity of actomyosin Mg2+-ATPase and the composition of troponin were investigated also. In seven Pietrain pigs halothane alone or with suxamethonium induced the malignant hyperthermia syndrome. In the animals with malignant hyperthermia Ca2+-ATPase was not activated in the plasma membranes of the muscle fibres, when compared with control animals (n = 4). An increase of Ca2+-ATPase of the sarcoplasmic reticulum was observed in animals with malignant hyperthermia; the opposite was noted in the control group. No significant changes in the activity of Mg2+-ATPase of the sarcoplasmic reticulum and of Mg2+-ATPase of actomyosin were observed after exposure to halothane in control pigs and those with malignant hyperthermia. The amount of troponin C was significantly changed in the animals with malignant hyperthermia. The mechanism of the development of malignant hyperthermia syndrome is discussed.
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PMID:Experimental porcine malignant hyperthermia: the activity of certain transporting enzymes and myofibrillar calcium-binding protein content in the muscle fibre. 612 63

The purpose of this study was to examine muscle plasmalemma which is implicated as the site responsible for the appearance of malignant hyperthermia in human and susceptible strains of animals. In pigs with malignant hyperthermia (MH) the activity of Na+/K+, Mg2+-ATPase, p-nitrophenylphosphatase and Mg2+-ATPase fell significantly during anaesthesia. In the control group the contrary occurred. In both the groups tested there was a marginal rise in the levels of sialic acid. The levels of cholesterol and lysoderivatives were abnormal before the provoking agents were administered but they changed significantly after onset of the MH syndrome. Anaesthesia reduced the phospholipids level in both tested animal groups. Before and after the provoking agents an impoverishment in the polypeptide pattern in the range between 80,000 and 30,000 daltons of mol. wt. in MH susceptible animals occurred. It is postulated that in MH the macromolecular disorganization of the muscle plasma membranes means that defence mechanisms maintaining cell gradients do not work in the presence of provoking agents.
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PMID:Experimental porcine malignant hyperthermia: macromolecular characterization of muscle plasma membranes. 615 Oct 35