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 direct effect of insulin on the high-affinity Ca2+-Mg2+-ATPase was studied in kidney proximal tubular basolateral membranes (BLM) obtained from control and streptozocin-induced non-insulin-dependent diabetes mellitus (NIDDM) rats. Plasma glucose of the diabetic animals was only mildly elevated (217 +/- 9 vs. 138 +/- 3 mg/dl). Both high- and low-affinity calcium-dependent Ca2+-Mg2+-ATPase activities were identified in the BLM. Enzyme activity in BLM from diabetic rats was higher at all Ca2+ concentrations tested due to a higher maximum velocity of the enzyme from NIDDM rats. The high-affinity Ca2+-Mg2+-ATPase activity was inhibited by trifluoroperazine (TFP) in both membranes. No difference in calmodulin content was found in the membranes from the diabetic and control rats. Insulin (16-200 microU/ml) significantly increased the high-affinity Ca2+-Mg2+-ATPase activity (17-40%) in membranes from control animals but had no effect on the enzyme activity in the membranes from the NIDDM rats. The basal activity of the enzyme at 0.1 microM free Ca2+ was higher in the BLM from the NIDDM animals compared to controls (17.8 +/- 0.5 vs. 14.7 +/- 0.8 nM Pi X mg-1 X min-1; P less than .02). There was no effect of insulin on the Ca2+-independent ATPase activity of BLM preparations. These findings demonstrate a defect in the ability of insulin to regulate the high-affinity Ca2+-Mg2+-ATPase activity in BLM from diabetic rats. Such a defect in enzyme activity may play a role in the mechanism of impaired insulin action observed in these NIDDM rats.
Diabetes 1986 Aug
PMID:Ca2+-Mg2+-ATPase activity in kidney basolateral membrane in non-insulin-dependent diabetic rats. Effect of insulin. 294 33

In rats, chronic diabetes is associated with depressed cardiac myosin ATPase activity and a shift from the predominant V1 isoenzyme to V3, correlating with depressed contractility. Rabbit myocardium consists mostly of the V3 isoenzyme, and therefore a switch to even more V3 isoenzyme in diabetes might not be possible and therefore not explain the mechanical abnormalities observed. To explore this, rabbits were made diabetic with 140-150 mg/kg of alloxan, and their hearts were studied 3 days, 1 mo, 3 mo, and 6 mo later. Ca2+-myosin-ATPase activity was decreased in the diabetic rabbit at 1, 3, and 6 mo, correlating with increased percent V3. Actin-activated Mg2+-ATPase activity was not significantly decreased in diabetics, but myofibrillar ATPase activity was decreased in 6-mo diabetic animals. When 3- to 4-mo diabetic animals were administered insulin for 3-4 additional months, myosin-ATPase activity and isoenzyme distribution normalized. These results correlate well with mechanical changes in papillary muscle from these same hearts. They suggest that in rabbit, as in rat, changes in cardiac contractile function are at least partially mediated by changes in myosin isoenzyme composition and are reversible with insulin.
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PMID:Effects of diabetes on cardiac contractile proteins in rabbits and reversal with insulin. 294 66

The present investigation was dedicated to support biochemical interpretations of well-known long-term microvascular complications in diabetes. Provided the hypothetical correlation between erythrocyte membrane rigidity and increased intracellular calcium content holds true, a reduced Ca2+-Mg2+-ATPase activity in diabetic subjects could represent the underlying biochemical mechanism. Thus, we have compared basal and calmodulin-activated ATPase activity in healthy and diabetic volunteers. We could demonstrate a significant reduction of basal and stimulated enzyme activity in diabetic subjects. Furthermore, partial purification of calmodulin from erythrocytes of diabetic patients and healthy subjects yielded experimental evidence that reduced enzyme activity in diabetic volunteers is due to an altered basal activity as well as to a reduced stimulation by calmodulin.
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PMID:Ca2+-Mg2+-ATPase activity of human red blood cells in healthy and diabetic volunteers. 295 58

The ATPase activity of myofibrils and myosin from hindlimb muscle was investigated in animals 4 wk after the induction of diabetes by an intravenous injection of streptozotocin (65 mg/kg). Ca2+-stimulated ATPase in myofibrils was increased in diabetic muscle at various times of incubation (1-7 min) as well as at different concentrations of free Ca2+ (10(-7)-10(-5) M Ca2+). Such an increase in Ca2+-stimulated ATPase was evident as early as 1 wk after streptozotocin injection, but Mg2+-ATPase activity remained unaltered. Treatment of diabetic animals with insulin Ca2+-ATPase and actin-activated ATPase activities of pure myosin were similarly increased in diabetic muscle. Myosin ATPase was also activated by K+- or NH4+-EDTA; these responses were more in diabetic muscle. However, sodium dodecyl sulfate gel electrophoresis failed to reveal differences in the patterns of contractile proteins, and pyrophosphate gels did not show significant changes in myosin isozyme patterns between diabetics and controls. The results of this study demonstrate an activation of contractile protein ATPase of skeletal muscle in diabetes and seem to indicate that such an alteration may be responsible for enhanced contractile function of skeletal muscle in this disease.
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PMID:Altered contractile proteins in skeletal muscle of diabetic rats. 295 57

The levels of the three ATPases found in the erythrocyte membrane of diabetic patients were significantly lower than normal subjects. The distribution of the enzymes was also different. Na+,K+-ATPase and Mg2+-ATPase reflected the status of blood glucose more than Ca2+-ATPase. The ratio between two of the ATPases was sensitive to glycemic response. When dikanut, a viscous preparation, was fed to diabetics for 4 weeks, blood glucose became normal and the activities of the three ATPases increased significantly. The ratio among the enzymes also approached that of normal subjects. A relationship was found between the blood glucose level and erythrocyte membrane ATPases which, if linked to insulin binding or level, may provide a rapid inexpensive assay in diabetes research.
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PMID:Erythrocyte membrane ATPases in diabetes: effect of dikanut (Irvingia gabonensis). 302 98

Na+-K+-dependent ouabain-sensitive ATPase and Mg2+-ATPase have been assayed in the erythrocyte membranes of control subjects and in uncontrolled type I (insulin-dependent) diabetics. A decrease in Na+-K+-ATPase activity was observed in the patients that was significantly correlated with glycemia. The Mg2+-ATPase was increased moderately, and no correlation with glycemia was found. To study the in vivo effect of insulin, ATPase activities were measured in uncontrolled diabetics before and after a 24-h continuous insulin perfusion administered by means of an artificial pancreas. ATPase activities were corrected after normalization of glycemia. It therefore seems that glycemia and/or insulinemia are involved in the regulation of erythrocyte Na+-K+ ouabain-sensitive ATPase and to a lesser extent in that of Mg2+-dependent ATPase.
Diabetes 1987 Sep
PMID:In vivo insulin effect on ATPase activities in erythrocyte membrane from insulin-dependent diabetics. 303 41

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

The effect of alloxan diabetes on the activities of Na+,K+-ATPase and Mg2+-ATPase was studied in three regions of rat brain at various time intervals after the onset of diabetes. It was observed that Na+,K+-ATPase activity increased at early time intervals after diabetes, followed by a recovery to near control levels in all three regions of the brain. There was an overall increase in Mg2+-ATPase activity in all the regions. A reversal of the effect was observed with insulin administration to the diabetic rats.
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PMID:Na+,K+-ATPase and Mg2+-ATPase activities in different regions of rat brain during alloxan diabetes. 612 23

Hyperglycemia leads to excess production of reactive oxygen species (ROS), lipid peroxidation and protein glycation that may impair cellular calcium homeostasis and results in calcium sequestration and dysfunction in diabetic tissues. Stobadine (ST) is a pyridoindole antioxidant has been postulated as a new cardio- and neuroprotectant. This study was undertaken to test the hypothesis that the treatment with ST inhibits calcium accumulation, reduces lipid peroxidation and protein glycation and can change Ca2+,Mg2+-ATPase activity in diabetic animals. The effects of vitamin E treatment were also evaluated and compared with the effects of combined treatment with ST. Diabetes was induced by streptozotocin (STZ, 55 mg/kg i.p.). Some of diabetic rats and their age-matched controls were treated orally with a low dose of ST (24.7 mg/kg/day), vitamin E (400-500 IU/kg/day) or ST plus vitamin E for 10 weeks. ST and vitamin E separately produced, in a similar degree, reduction in diabetes-induced hyperglycemia. Each antioxidant alone significantly lowered the levels of plasma lipid peroxidation, cardiac and hepatic protein glycation in diabetic rats but vitamin E treatment was found to be more effective than ST treatment alone. Diabetes-induced increase in plasma triacylglycerol levels was not significantly altered by vitamin E treatment but markedly reduced by ST alone. The treatment with each antioxidant completely prevented calcium accumulation in diabetic heart and liver. Microsomal Ca2+,Mg2+-ATPase activity significantly decreased in both tissues of untreated diabetic rats. ST alone significantly increased microsomal Ca2+,Mg2+-ATPase activity in the heart of normal rats. However, neither treatment with ST nor vitamin E alone, nor their combination did change cardiac Ca2+,Mg2+-ATPase activity in diabetic heart. In normal rats, neither antioxidant had a significant effect on hepatic Ca2+,Mg2+-ATPase activity. Hepatic Ca2+,Mg2+-ATPase activity of diabetic rats was not changed by single treatment with ST, while vitamin E alone completely prevented diabetes-induced inhibition in microsomal Ca2+,Mg2+-ATPase activity in liver. Combined treatment with ST and vitamin E provided more benefits in the reduction of hyperglycemia and lipid peroxidation in diabetic animals. This study describes potential mechanisms on cellular effects of ST in the presence of diabetes-induced hyperglycemia that may delay or inhibit the development of diabetic complications. The use of ST together with vitamin E can better control hyperglycemia-induced oxidative stress.
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PMID:In vivo treatment with stobadine prevents lipid peroxidation, protein glycation and calcium overload but does not ameliorate Ca2+ -ATPase activity in heart and liver of streptozotocin-diabetic rats: comparison with vitamin E. 1237 16

Previous studies have shown that the renin-angiotensin system (RAS) is activated in diabetes and this may contribute to the subcellular remodelling and heart dysfunction in this disease. Therefore, we examined the effects of RAS blockade by enalapril, an angiotensin-converting enzyme inhibitor, and losartan, an angiotensin receptor AT1 antagonist, on cardiac function, myofibrillar and myosin ATPase activity as well as myosin heavy chain (MHC) isozyme expression in diabetic hearts. Diabetes was induced in rats by a single injection of streptozotocin (65 mg/kg; i.v.) and these animals were treated with and without enalapril (10 mg/kg/day; oral) or losartan (20 mg/kg/day; oral) for 8 weeks. Enalapril or losartan prevented the depressions in left ventricular rate of pressure development, rate of pressure decay and ventricular weight seen in diabetic animals. Both drugs also attenuated the decrease in myofibrillar Ca2+-ATPase, Mg2+-ATPase and myosin ATPase activity seen in diabetic rats. The diabetes-induced increase in beta-MHC content and gene expression as well as the decrease in alpha-MHC content and mRNA levels were also prevented by enalapril and losartan. These results suggest the occurrence of myofibrillar remodelling in diabetic cardiomyopathy and provide evidence that the beneficial effects of RAS blockade in diabetes may be associated with attenuation of myofibrillar remodelling in the heart.
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PMID:Renin-angiotensin blockade attenuates cardiac myofibrillar remodelling in chronic diabetes. 1536 13


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