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)

The effect of culture conditions, serum supplementation or chemically defined medium and the influence of thyroid hormone were studied on the development of the Na+, K+-adenosine triphosphatase (Na+,K+-ATPase) and on the intracellular content of K+ and Na+ ions in cultures which either were greatly enriched in a neuronal cell type, the cerebellar granule cells, or contained a mixed population of cells (brain reaggregates). Foetal rat brain reaggregates displayed lower Na+,K+-ATPase activity when cultured in chemically defined medium than in the presence of serum. Supplementation of the serum-free medium with thyroid hormone resulted in a rise in the Na+,K+-ATPase activity and [3H]ouabain binding to levels similar to those found in the cultures grown in the serum-containing medium. Thyroid hormone had no significant effect on the Mg2+-ATPase activity and on the intracellular content of Na+ and K+ ions. In the granule cell-enriched cerebellar surface cultures the Na+,K+-ATPase activity was lower when the cells were grown in chemically defined medium compared with the serum-containing medium, and the intracellular Na+ to K+ ratio was higher. Thyroid hormone had no effect on the Na+,K+-ATPase activity, [3H]ouabain binding or Mg2+-ATPase activity. The hormone also failed to influence ATPase activities in cerebellar astrocytes maintained in chemically defined medium. Although thyroid hormone had no effect on the Na+,K+-ATPase activity of cultured cerebellar granule cells, treatment with the hormone resulted in a decrease in the ratio of intracellular Na+ to K+ ion content. The effect of the hormone on the Na+,K+-pump activity in live cells was therefore tested by estimating ouabain-sensitive 86Rb uptake. This was regulated as in other cell types, by the rate of Na+ entry: the Na+-ionophore monensin trebled the rate of 86Rb uptake, which was also increased (+30-100%) by 10% foetal calf serum, the maximal response being obtained by about 20 min exposure to serum. The effect was completely blocked by the Na+/H+ exchange inhibitor amiloride. The factor(s) in the serum responsible for the regulation of the Na+,K+-pump were, however, not the thyroid hormones, which failed to affect 86Rb uptake. On the basis of comparing thyroid hormone effects on the different cultures studied it was concluded that not every type of neural cell is target of the hormone action during development.
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PMID:Effect of thyroid hormone and serum on the development of Na+, K+-adenosine triphosphatase and associated ion fluxes in cultures from rat brain. 298 59

Diabetes was induced in rats by an intravenous injection of streptozotocin (65 mg/kg body wt), and animals were killed 8 wk later. Some animals were maintained in a diabetic state for 6 wk and then given 2 wk of insulin treatment in vivo. Myofibrils were isolated and ATPase activities measured. Mg2+-ATPase and Ca2+-stimulated ATPase activities were depressed in diabetic rat hearts in comparison to control; insulin treatment normalized these activities. The depression in myofibrillar ATPases was of gradual onset as no changes were detected 2 wk after inducing diabetes. Treatment of diabetic animals with thyroid hormone did not restore changes in myofibrillar ATPase activities. Marker enzyme activities did not reveal any detectable contamination by cardiac membranes. Mg2+-ATPase activity of myofibrillar preparations from control and diabetic hearts responded differently to N-ethylmaleimide modification. Furthermore, myofibrillar sulfhydryl reactivity to 5,5'-dithiobis(2-nitrobenzoic acid) was significantly depressed in diabetic preparations in comparison to control and insulin-treated diabetic animals. These results suggest that the defect in myofibrillar ATPase activities in chronic diabetes may be due to some modification of sulfhydryl groups.
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PMID:Mechanisms of the defect in cardiac myofibrillar function during diabetes. 315 18

We tested whether changes in cardiac myosin ATPase activity induced by swimming exercise in male rats are due to a redistribution of existing isoenzymic forms of ventricular myosin. The isoenzymic profiles were analyzed by nondissociating gel electrophoresis of ventricular samples and compared with ATPase activities of myofibrils prepared from the same ventricle. Myofibrils prepared from hearts of rats in the control sedentary group or from hearts of rats in the groups of 8- or 12-wk swimmers had the same actomyosin Mg2+-ATPase activities measured between pCa 8 and 5. However, the myosin Ca2+-ATPase activity of myofibrils prepared from hearts of 8- or 12-wk swimmers was 20% higher than the activity of control preparations. This increase in activity was in proportion to an increase in the relative amount of V1, the myosin isoenzyme with the highest Ca2+-ATPase activity. Thyroidectomized rats, whose hearts had no detectable V1, were also subjected to the swimming program. In the case of the hypothyroid rats, myofibrillar preparations from controls and 8- or 12-wk swimmers had the same actomyosin Mg2+-ATPase activity, myosin Ca2+-ATPase activity, and the same isoenzyme profiles. Co-electrophoresis of ventricular samples from the euthyroid and hypothyroid controls and swimmers showed no evidence for new variants of myosin. We conclude that the increase in myosin Ca2+-ATPase activity in the ventricles of euthyroid swimmers is due to a redistribution of existing isoforms of myosin and that the redistribution process may require thyroid hormone for its expression.
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PMID:Swimming exercise, thyroid state, and the distribution of myosin isoenzymes in rat heart. 613 25