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)

Aldose reductase (EC 1.1.1.21) is implicated in the pathophysiology of diabetic complications. In this paper we determined the activities of aldose reductase and ATPases of the erythrocytes in 17 patients with Type 2 (non-insulin-dependent) diabetes mellitus (NIDDM). In the aldose reductase assay we used fluorometric method to avoid the disturbance of hemoglobin. With dihydronicotinamide adenine dinucleotide (NADH), we verified it was aldose reductase but not aldehyde reductase II that was activated in the erythrocytes of the patients with NIDDM. The aldose reductase activity of the erythrocytes in the patients was significantly higher (P less than 0.01) than that in the controls. The activity of Na+/K(+)-ATPase of the patients was significantly lower (P less than 0.01) than that of the controls. The activities of Ca(2+)-ATPase and Mg(2+)-ATPase on the erythrocyte membranes of the patients were similar to those of the controls. At the same time we measured the seven nucleotide concentrations in the erythrocytes of the patients. In this experiment we used ultrafiltration method, instead of acid precipitation to make it possible to determine dihydronicotinamide adenine dinucleotide phosphate (NADPH) and NADH. The concentrations of ATP, ADP and AMP were similar to those of the controls. The concentrations of NADPH, NAD+ and NADH in the erythrocytes of the patients were significantly lower (P less than 0.01, 0.05 and 0.05 respectively) than those of controls. The concentration of nicotinamide adenine dinucleotide phosphate (NADP+) in the patients was significantly higher (P less than 0.01) than that of controls.
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PMID:Activities of aldose reductase, ATPases, and nucleotide concentrations of erythrocytes in patients with type 2 (non-insulin-dependent) diabetes mellitus. 166 Dec 22

Intraperitoneal administration of a single dose (6 mg/kg body wt.) of mercuric chloride led to a rapid and irreversible inhibition of Na+/K(+)-ATPase activity in rat cerebral capillaries. The activity measured at 1 h, 18 h and 5 days after injection was, respectively, 53, 44 and 26% of the control. By contrast, Mg(2+)-ATPase activity in the capillaries remained uninhibited throughout the observation period. Mercuric chloride administration did not affect either of the two enzyme activities in nerve endings, which is consistent with the inability of the compound to penetrate the blood-brain barrier. The mercuric-chloride-induced impairment of the capillary sodium pump may contribute to disturbances of ion homeostasis in the brain and thus to the neurophysiological abnormalities accompanying this exposure. Direct treatment of the isolated cerebral capillary preparations with mercuric chloride evoked a stronger inhibitory effect on Mg(2+)-ATPase (IC50 = 0.25 microM) than on Na+/K(+)-ATPase (IC50 = 5.0 microM). This result indicates that the effect in vivo may not have resulted from direct interaction of the compound with the latter enzyme.
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PMID:Durable inhibition of rat cerebral capillary Na+/K(+)-ATPase after in vivo administration of mercuric chloride. 166 49

Triorganotins have been reported to affect heme metabolism as well as the cardiovascular system. Our recent studies indicated that these organotins inhibit cardiac sarcoplasmic reticulum Ca(2+)-transport and cAMP-stimulated phosphorylation of specific proteins involved in Ca2+ transport, suggesting their interference with cardiac adrenergic function. The present study determines the effect of three organotins--tributyltin bromide (TBT), triethyltin bromide (TET) and trimethyltin chloride (TMT)--on rat cardiac ATPases and catecholamine binding, since these phenomena are involved in cardiac function. Cardiac membrane fraction was prepared from heart ventricles of male Sprague-Dawley rats. All three organotins inhibited cardiac Na+,K(+)-ATPase, [3H]ouabain binding, K(+)-activated p-nitrophenyl phosphatase (K(+)-PNPPase) and oligomycin-sensitive (OS) and oligomycin-insensitive (OI) Mg(2+)-ATPase in a concentration-dependent manner. K(+)-PNPPase was less sensitive to these triorganotins when compared to Na+K(+)-ATPase, suggesting that triorganotins affect the Na(+)-pump activity by acting on the Na(+)-dependent phosphorylation process. OS Mg(2+)-ATPase was more sensitive to these organotins when compared to OI Mg(2+)-ATPase, confirming their potent effect on the enzymes of oxidative phosphorylation. The order of potency is TBT greater than TET greater than TMT. TET and TMT, but not TBT, inhibited [3H]norepinephrine and [3H]dopamine binding to cardiac membranes in a concentration-dependent manner, the effect being more with TET. These results suggest that triorganotins inhibit sodium pump activity as well as ATP synthesis. Since Na+,K(+)-ATPase is involved in the active transport of catecholamines, triorganotins not only inhibited the catecholamine transport but also to some extent affected catecholamine binding, thus interfering with cardiac function.
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PMID:Triorganotin inhibition of rat cardiac adenosine triphosphatases and catecholamine binding. 166 43

Cytochemical techniques associated with transmission electron microscopy were used for the localization in Tritrichomonas foetus of enzymes used as markers of different cell structures. Reaction product indicating the presence of Mg(2+)-adenosine triphosphatase (Mg(2+)-ATPase) and 5'-nucleotidase was observed in the plasma membrane. Glucose-6-phosphatase was seen in association with the endoplasmic reticulum, revealing its organization as parallel cisternae. Thiamino-pyrophosphatase was located in the cis-most region of the Golgi complex. Acid phosphatase was found within lysosomes as well as in several cisternae of the Golgi complex, in contrast to previous observations in mammalian cells. These observations provide support for the use of enzyme markers in future studies on cell fractionation of T. foetus.
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PMID:Cytochemical localization of enzyme markers in Tritrichomonas foetus. 166 35

Na+,K(+)-ATPase and Ca(2+)-ATPase in testis were inhibited with an oral administration of cimetidine and ranitidine. Cimetidine at dose level of 100 and 30 mg while ranitidine at 70 and 10 mg per kg body wt inhibited the enzyme activities, 24 hr after single administration or daily administration for 15-days. Mg(2+)-ATPase activity was increased with cimetidine while ranitidine inhibited the enzyme. Michaelis-Menten kinetic characteristics revealed mixed type of inhibition for Na+,K(+)-ATPase with cimetidine, whereas it was noncompetitive for Ca(2+)-ATPase with cimetidine as well as ranitidine administration. Inhibition of Na+,K(+)-ATPase with ranitidine was also of noncompetitive type. Mg(2+)-ATPase behaved differently with administration of ranitidine at both the time points used i.e. noncompetitive type of inhibition after 24 hr and mixed type after 15-days. Histologically, signs of degeneration of testicular elements appeared after administration of cimetidine with a significant decrease in tubular diameter and germinal epithelial cell height. Ranitidine administration did not produce any change in the seminiferous tubules of testis. Scanning electron microscopy of spermatozoa from cimetidine-treated mice exhibited distinct departure from the normal morphology such as, (i) breaks at various places along distal portion of the tail, (ii) roughening, wrinkling and disorganization of plasma membrane of the head region, (iii) decapitation of the head and (iv) changes in shape of cytoplasmic droplet. Ranitidine administration showed normal morphology of the spermatozoa.
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PMID:Effect of H2-receptor antagonists, cimetidine and ranitidine on reproductive functions in male mice. 166 45

To investigate the role of Cl(-)-stimulated Mg(2+)-ATPase (Cl(-)-ATPase) in neurons, we examined the effects of ethacrynic acid (0.3 mM), which completely inhibits Cl(-)-ATPase on the intracellular Cl- concentrations of cultured rat hippocampal neurons, using Cl(-)-sensitive fluorescent probes. Ethacrynic acid and ATP consuming treatment increased the intracellular Cl- concentration, but elevation of the extracellular K+ concentration up to 10 mM, inhibition of Na+/K(+)-ATPase, or dissolution of H+ gradients had no effect. Furosemide (0.1 mM), an inhibitor of Na+/K+/Cl- co-transport, decreased the intracellular Cl- concentrations. These results indicate that an ethacrynic acid-sensitive and ATP-driven Cl- pump functions to reduce intraneural Cl- concentrations.
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PMID:An ATP-driven Cl- pump regulates Cl- concentrations in rat hippocampal neurons. 166 80

In the present work we reported the results of the study of erythrocyte membrane Na+,K(+)-adenosine triphosphatase (ATPase) and Mg(2+)-ATPase in patients with essential hypertension and controls. In the 40 patients with hypertension, a more marked decrease of Na+, K(+)-ATPase was observed. The behavior of the enzyme at Mg2+ activation, ouabain inhibition and the response to different temperature suggest the possibility of differences between the two groups. The normal erythrocyte Mg(2+)-ATPase activity in two groups suggest also the possible role of ratio Na+, K(+)-ATPase/Mg(2+)-ATPase in the study of essential hypertension. However the relevance of magnesium and Mg(2+)-ATPase to the pathogenesis of essential hypertension remains unclear but merits further study. On the basis of these considerations the aim of the present study was to identify, in a kinetic approach, the presence of different abnormalities of Na+ transport and Na+, K(+)-ATPase in erythrocytes from patients with essential hypertension. Much evidence has supported the hypothesis that essential hypertension is a heterogeneous disease in the pathophysiological mechanisms as well as in its clinical and therapeutical consideration.
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PMID:[Various properties of the Na+, K(+)-ATPase and the Mg (2+)-ATPase in erythrocytes from normotensive and hypertensive subjects]. 166 78

The effect of tetrandrine (Tet) on Na+,K(+)-ATPase and Mg(2+)-ATPase in rat myocardial microsomes was investigated in vitro. Under optimal condition, Tet did not influence Na+,K(+)-ATPase activity but concentration-dependently inhibited Mg(2+)-ATPase with an IC50 of 179 mumol/L. At 10 or 100 mumol/L, Tet caused the concentration-inhibition curves for ouabain a parallel shift to the right. Tet 100 mumol/L markedly increased the activity of Na+,K(+)-ATPase under suboptimal K+ or excessive Ca2+ condition. However, it did not significantly increase the enzyme activity when the Na+ concentration was lower. A kinetic analysis showed that Tet increased the affinity of Na+,K(+)-ATPase to ATP, but did not change the maximal velocity of the enzyme reaction.
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PMID:[The effect of tetrandrine on rat myocardial ATPases]. 166 15

In renovascular hypertensive rats (RVHR, two-kidney, one-clip model), the myocardial Na+, K(+)-ATPase showed a reduced activity. Though its sensitivities to K+ and ouabain (Oua) were not changed, the enzyme was less responsive to Na+ and ATP, and also much more susceptible to the inhibitory effect of Ca2+. Tetrandrine (Tet, ig 50 mg.kg-1, qd x 26 d) increased the myocardial Na+, K(+)-ATPase activity in RVHR. However, in vitro, Tet elevated moderately the enzyme activity in RVHR only at high concentrations (100-1,000 mumol.L-1), and failed to influence the enzyme activity in normotensive rats. In RVHR, treatment by Tet in vivo increased the degree of the Na+, K(+)-ATPase activation under suboptimal substrate (Na+, K+, or ATP) concentrations and antagonized the inhibitory effect of Ca2+ or Oua. Similar results were found when the enzyme preparation from RVHR was incubated with Tet 10 mumol.L-1 during ATPase analysis. On the contrary, the myocardial Mg(2+)-ATPase activity was higher in RVHR. Tet depressed this enzyme both in vivo and in vitro. These facts indicate that the increased myocardial Na+, K(+)-ATPase activity in RVHR is not only secondary to the calcium channel blocking or antihypertensive action of Tet but also due to its direct effects on the Na+, K(+)-ATPase and Mg(2+)-ATPase.
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PMID:Effect of tetrandrine on myocardial Na+, K(+)-ATPase in renovascular hypertensive rats. 166 64

Rat brain synaptosomal Na(+)-K(+)-ATPase was activated by Panax notoginseng (PNS, 0.1-1.0 mg.ml-1), fraction Rb1 (25-200 micrograms.ml-1), and fraction Rg1 (50-200 micrograms.ml-1). Activating rates were respectively 84-227%, 12-48%, and 12-22%. Results implied that Rb1 and Rg1 were not the major components of PNS, which were responsible for the activating effects. Ca(2+)-Mg(2+)-ATPase was inhibited by PNS (0.1-1.0 mg.ml-1) and Rb1 (100-200 micrograms.ml-1), but not by Rg1. It was proposed that PNS activated Na(+)-K(+)-ATPase, leading to a reduced Na+/Ca2+ exchange, a lowered intracellular Ca2+ level, and heart contractility.
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PMID:Effects of saponins of Panax notoginseng on sodium-potassium-adenosine triphosphatase and calcium-magnesium-adenosine triphosphatase. 166 65


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