Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Content of lactate, pyruvate as well as activity of hexokinase, phosphorylases, ATPase and transaminases were studied in dog and rat liver tissues under conditions of acute profuse hemorrhage and after its complete compensation by autogenic, isogenic blood and by sodium chloride 0.9% solution. Distinct inhibition of the hexokinase activity in the hemorrhage led to impairment of glucose utilization in liver tissue and to development of hyperglycemia. Alterations in arterial blood pressure correlated with the activity of tissue enzymes. Tissue metabolism was improved after compensation of blood losses by adequate amounts of blood at early period of hemorrhagic shock.
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PMID:[Liver metabolism during massive hemorrhage and subsequent blood transfusion]. 14 25

Detailed studies of hepatic metabolism of lipemic BHE and nonlipemic Wistar rats were conducted. Hepatic lipogenic capacity was varied through the use of starvation or meal feeding. Livers were clamped in precooled copper plates and used for the assay of glycolytic, gluconeogenic, and lipogenic metabolites. Redox and phosphorylation states were calculated. Mitochondrial metabolism was evaluated through studies of the oxygen consumption of isolated mitochondria and through the study of the activities of the alpha-glycerophosphate and malate aspartate shuttles and ATPase. BHE rats have higher phosphorylation states, higher redox ratios, and lower shuttle activities and oxygen consumption by isolated mitochondria than their Wistar cohorts. The differences in oxidative phosphorylation, redox and phosphorylation states, and in the various shuttle activities suggest that BHE liver cells are geared towards lipogenesis at the expense of oxidative phosphorylation. It appears that the activity of the shuttles is controlled in part by phosphorylation state which in turn appears to affect respiration. We theorize from these data that genetically determined differences in the structure and function of the mitochondrial membrane (and perhaps the cell membrane as well) may affect the communication (via metabolites and adenine nucleotides) between the cytosol and mitochondria. Subtle differences in the exchange of metabolites and/or adenine nucleotides across the mitochondrial membrane could thus explain the lipogenic tendency of the liver of the BHE rat and the subsequent development of maturity onset hyperlipemia and hyperglycemia in this strain of rat.
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PMID:Studies on the control of lipogenesis: strain differences in hepatic metabolism. 43 Feb 26

Trapymin (TM) relaxed excised renal, coronary, pulmonary, femoral and mesenteric arteries and this relaxation was not antagonized by propranolol. The dose-response curve of TM was parallel to that of nitroglycerin and papaverine and steeper than that of dipyridamol or adenosine. TM exerted inotropic and chronotropic actions on excised rat atrium. TM was also effective through the oral route and the effectiveness tended to decrease slightly after repeated use for ten days. TM was effective on vasopressin induced angina in rats and electrocoagulation-induced myocardial infarction. TM suppressed adrenaline-induced arrhythmia but not CaCl2-induced arrhythmia. TM reduced catecholamine content in brain, adrenals and heart but had no influence on monoamine oxidase or dopamine-beta-hydroxylase. TM revealed ganglion-blocking and neuron-blocking actions in cervical ganglion in cats. With propranolol, TM-induced hyperglycemia and reduction in glycogen content in liver and heart was antagonized but TM-induced rise in free fatty acid in serum was not antagonized. Na+-K+ dependent ATPase of bovine heart and P/O ratio of mitochondria of rat heart was not influenced by TM. ADP-induced aggregation of platelets was antagonized by TM. These data indicate that TM induced coronary dilation is partly due to a papaverine like action and also to ganglion-blocking, neuron-blocking and anti-adrenergic action. On the other hand, TM possessed catecholamine release and cardiotonic action as related to beta-receptors.
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PMID:[Pharmacology of cornary dilator agent, trapymin. (2) Analysis of its mode of action]. 124 70

We have examined the effects of diabetes, fasting, and refeeding on Na+/K(+)-adenosine triphosphatase (ATPase) activity and its catalytic alpha II subunit gene expression in skeletal muscle. Two hypoinsulinemic states, streptozotocin-induced diabetes and 48-hour fasting caused a significant decrease (P less than .05) in skeletal muscle Na+/K(+)-ATPase activity and a marked increase (P less than .01) in the levels of alpha II subunit mRNA. A decrease in enzyme activity was observed on the 2nd and the 14th day of diabetes, whereas an increase in alpha II mRNA levels was found only on the 14th day. The levels of alpha I mRNA were not affected, while the levels of mRNA of the structural beta subunit were decreased on the 14th day of diabetes. Correction of hyperglycemia with insulin restored enzyme activity and alpha II isoform mRNA levels toward normal in diabetic animals. Refeeding for 48 or 72 hours restored these parameters to normal in skeletal muscle of previously fasting rats. These observations suggest that a decrease in muscle Na+/K(+)-ATPase activity may lead to a compensatory increase in its alpha II subunit gene expression. The levels of insulin and not of glycemia appear to be critical in modulating Na+/K(+)-ATPase activity and gene expression.
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PMID:Na+/K(+)-ATPase activity and its alpha II subunit gene expression in rat skeletal muscle: influence of diabetes, fasting, and refeeding. 131 3

It has been proposed that abnormal myo-inositol metabolism may be a factor in the development of diabetic complications. Studies with animal models of diabetes and cultured cells have suggested that hyperglycemia by an unknown mechanism may alter myo-inositol metabolism and content. Recently, we have shown that L-fucose, a 6-deoxy sugar whose content has been reported to be increased in diabetes, is a potent inhibitor of myo-inositol transport. To examine the effect of L-fucose on myo-inositol metabolism, neuroblastoma cells were cultured in medium supplemented with L-fucose. L-Fucose is a competitive inhibitor of Na(+)-dependent, high-affinity myo-inositol transport. The Ki for inhibition of myo-inositol transport by L-fucose is about 3 mM. L-Fucose is taken up and accumulates in neuroblastoma cells. The uptake of L-fucose is inhibited by Na+ depletion, D-glucose, glucose analogues, phloridzin, and cytochalasin B. In contrast, neither myo-inositol nor L-glucose inhibits L-fucose uptake. Chronic exposure of neuroblastoma cells to 1-30 mM L-fucose causes a decrease in myo-inositol accumulation and incorporation into inositol phospholipids, intracellular free myo-inositol content, and phosphatidylinositol levels. Na+,K(+)-ATPase transport activity is decreased by about 15% by acute or chronic exposure of neuroblastoma cells to L-fucose. Similar defects occur when neuroblastoma cells are exposed chronically to 30 mM glucose. Cell myo-inositol metabolism and Na+/K(+)-pump activity are maintained when 250 microM myo-inositol is added to the L-fucose-supplemented medium. Unlike the effect of chronic exposure of neuroblastoma cells to medium containing 30 mM glucose, the resting membrane potential of neuroblastoma cells is not altered by chronic exposure of the cells to 30 mM L-fucose. The effect of L-fucose on cultured neuroblastoma cell properties occurs at concentrations of L-fucose which may exist in the diabetic milieu. These data suggest that increased concentrations of L-fucose may have a role in myo-inositol-related defects in mammalian cells.
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PMID:L-fucose is a potent inhibitor of myo-inositol transport and metabolism in cultured neuroblastoma cells. 131 50

The acute effects of 2-deoxy-D-glucose (2-DG)-induced glucoprivic feeding on the anorectic drug recognition site and Na+K(+)-ATPase in the brain were examined in adult rats and in lean and genetically obese mice. The marked hyperglycemia and the induction of feeding caused by the administration of 2-DG to satiated rats and lean mice were associated with significant increases in Na+K(+)-ATPase activity, and in [3H]ouabain binding and [3H]mazindol binding to the anorectic drug recognition site in hypothalamic membranes. Basal and 2-DG-stimulated levels of blood glucose were significantly correlated to the levels of hypothalamic [3H]ouabain (r = + .91, p less than 0.01) and [3H]mazindol (r = + .87, p less than 0.01) binding. A significant correlation (r = .74, p less than 0.05) was also observed between [3H]mazindol binding and [3H]ouabain binding supporting the hypothesis that these hypothalamic binding sites are functionally coupled in their response to circulating glucose. Following the intracerebroventricular (ICV) administration of the diabetogenic drug alloxan, 2-DG did not stimulate feeding or increase [3H]mazindol and [3H]ouabain binding sites in the hypothalamic paraventricular area. Since 2-DG still caused hyperglycemia in alloxan-treated rats, alloxan-induced inactivation of glucoreceptor mechanisms led to an uncoupling of the anorectic drug recognition site from a hypothalamic glucostat. In genetically obese mice (ob/ob), 2-DG also could not induce feeding or increase hypothalamic [3H]ouabain or [3H]mazindol binding, despite a significant hyperglycemic response. In contrast, 2-DG did increase feeding and the binding of [3H]ouabain and [3H]mazindol to the hypothalamus of lean littermates.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Regulation of the anorectic drug recognition site during glucoprivic feeding. 131 40

Hyperglycemia has been shown to diminish Na(+)-K+ ATPase activity in rabbit aorta. To examine the basis for this effect, aortic rings were incubated for 3 h in Krebs-Henseleit solution containing 5.5 or 44 mM glucose, and Na(+)-K+ ATPase activity was then quantified on the basis of ouabain-sensitive (OS) 86Rb-uptake. Incubation with 44 mM glucose medium caused a 60% decrease in Na(+)-K+ ATPase activity in rings with intact endothelium (from 0.22 +/- 0.01 to 0.091 +/- 0.006 nmol/min per mg dry wt; P less than 0.01). Similar decreases (45%; P less than 0.01) in Na(+)-K+ ATPase activity were seen when rings incubated with 5.5 mM glucose were exposed to NG-monomethyl L-arginine (300 microM), an inhibitor of endothelium-derived nitric oxide (EDNO) synthesis or when the endothelium was removed (43% decrease). The decrease in Na(+)-K+ ATPase activity induced by hyperglycemia was totally reversed upon adding to the medium either L-arginine, a precursor of EDNO biosynthesis or sodium nitroprusside, which bypasses endothelium and directly activates the soluble guanylate cyclase in vascular smooth muscle. A decrease in Na(+)-K+ ATPase activity (42%; P less than 0.05), only seen in the presence of endothelium, was also observed in aortas taken directly from alloxan-induced diabetic rabbits. These studies suggest that the decrease in vascular Na(+)-K+ ATPase activity induced by hyperglycemia is related, at least in part, to a decrease in the basal release of EDNO. They also suggest that alterations in basal EDNO release and possibly Na(+)-K+ ATPase activity contribute to the impairment in vascular relaxation caused by hyperglycemia and diabetes.
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PMID:Endothelium-dependent inhibition of Na(+)-K+ ATPase activity in rabbit aorta by hyperglycemia. Possible role of endothelium-derived nitric oxide. 132 96

This study evaluated the effect of chronic hyperglycemia on erythrocyte membrane Ca and Na/K-ATPase activities in streptozotocin-induced diabetic rats. The activity of Ca-ATPase was significantly lower in diabetic than in normal rats. Good glycemic control by insulin restored the Ca-ATPase activity to normal. By contrast, diltiazem, a calcium entry blocker, had no effect on the enzyme activity. Calmodulin stimulated Ca-ATPase activity in all groups of rats. Na/K-ATPase activity was not altered in diabetic rats, and no effects of either insulin or diltiazem treatments were observed. The results suggest that erythrocyte Ca-ATPase activity is decreased in diabetic rats and is normalized by good glycemic control.
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PMID:Erythrocyte Ca, Na/K-ATPase in long-term streptozotocin diabetic rats. Effect of good glycemic control and a Ca antagonist. 133 57

Epidemiological and clinical data suggest a relationship between hyperinsulinism and macroangiopathy in non insulin-dependent diabetes. On the other hand, a relationship between the plasma free insulin level and macroangiopathy has not been documented in insulin-dependent diabetes. Other abnormalities in addition to hyperinsulinism and glucose intolerance are frequently associated in the presence of insulin resistance and have been grouped by Reaven under the term syndrome X: raised VLDL triglycerides, decreased HDL, and raised blood pressure. Iatrogenic hyperinsulinism appears to be an arterial risk factor, but by what mechanism may it also constitute an independent risk factor? The following theoretical aspects of a possible atherogenic role of hyperinsulinism are currently being investigated: a) insulin stimulates the proliferation and migration of smooth muscle cells either directly or via a rise in IGF1; b) insulin induces lipogenesis in the intima-media, but it has not been demonstrated that this in situ lipogenesis is atherogenic; c) insulin raises the VLDL production, decreases HDL and modifies the clearance of LDL; d) insulin increases blood pressure by stimulating both the renal reabsorption of sodium and the sympathetic nervous system; insulin resistance may also be expressed at the level of the Na-K-ATPase of vascular smooth muscle cells by decreasing the vasodilator effect of the hormone; e) lastly, insulin induces a defect of fibrinolysis mediated by an increase in the level of plasminogen activator inhibitors (PAI1). In conclusion, the combination of hyperglycemia and hyperinsulinism is probably damaging to the artery. Therapeutic intervention studies are necessary to confirm and define the role of hyperinsulinism in macroangiopathy and to answer the unresolved questions: direct or indirect role? effect of endogenous and/or exogenous hyperinsulinism?
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PMID:[Theoretical aspects of the relationship between diabetic macroangiopathy and hyperinsulinism]. 143 1

The most common form of neuropathy associated with diabetes mellitus is distal symmetric sensorimotor polyneuropathy, often accompanied by autonomic neuropathy. This disorder is characterized by striking atrophy and loss of myelinated and unmyelinated fibers accompanied by Wallerian degeneration, segmental, and paranodal demyelination and blunted nerve fiber regeneration. In both humans and laboratory animals, this progressive nerve fiber damage and loss parallels the degree and/or duration of hyperglycemia. Several metabolic mechanisms have been proposed to explain the relationship between the extent and severity of hyperglycemia and the development of diabetic neuropathy. One mechanism, activation of the polyol pathway by glucose via AR, is a prominent metabolic feature of diabetic rat peripheral nerve, where it promotes sorbitol and fructose accumulation, myo-inositol depletion, and slowing of nerve conduction by alteration of neural Na(+)-K(+)-ATPase activity or perturbation of normal physiological osmoregulatory mechanisms. ARIs, which normalize nerve myo-inositol and nerve conduction slowing, are currently the focus of clinical trials. Other specific metabolic abnormalities that may play a role in the pathogenesis of diabetic neuropathy include abnormal lipid or amino acid metabolism, superoxide radical formation, protein glycation, or potential blunting of normal neurotrophic responses. Metabolic dysfunction in diabetic nerve is accompanied by vascular insufficiency and nerve hypoxia that may contribute to nerve fiber loss and damage. Although major questions about the pathogenesis of diabetic neuropathy remain unanswered and require further intense investigation, significant recent progress is pushing us into the future and likely constitutes only the first of many therapies directed against one or more elements of the complex pathogenetic process responsible for diabetic neuropathy.
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PMID:Complications: neuropathy, pathogenetic considerations. 146 45


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