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)

(Na+,K+)ATPase activity in synaptic membranes from whole brains of mice was inhibited by a series of short-chain aliphatic alcohols (ethanol through pentanol). The relationship of inhibitory potency to alcohol chain length and to alcohol membrane:water partition coefficient suggested that the inhibitory effect of the alcohols does not depend totally on their interaction with neuronal membrane lipids. Although partitioning into the membranes is important for this inhibitory effect, a direct interaction of alcohol with the enzyme protein may also be involved in the inhibition. Norepinephrine did not significantly potentiate inhibition of (Na+,K+)ATPase activity by low concentrations of ethanol in preparations of either mouse or rat brain. Thus, under our conditions, ethanol, at levels which can be reached in vivo, only slightly inhibited enzyme activity, and the possible importance of this inhibition in mediating the in vivo acute or chronic effects of ethanol on the CNS remains open to question.
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PMID:Effects of short-chain alcohols and norepinephrine on brain (Na+,K+)ATPase activity. 301 5

Effects of K+, ethanol and norepinephrine on the binding kinetics of ouabain to (Na+,K+)-adenosine triphosphatase in beef brain microsomes were examined. K+ reduced the rate and apparent affinity for ouabain binding markedly. Whereas ethanol and norepinephrine themselves inhibited ouabain binding slightly, they stimulated binding in the presence of K+. Norepinephrine enhanced the effect of ethanol. Dissociation of ouabain was biphasic, with fast and slow components corresponding to high and low apparent affinity. About 65% of the enzyme had high affinity, regardless of conditions. Norepinephrine and ethanol had differential effects on the rate of dissociation from high and low affinity enzyme, however. Alpha receptor blockade generally prevented the effects of norepinephrine. These results show that, although norepinephrine and ethanol have a modest effect on the amount of enzyme that can bind ouabain, their main effect on (Na+,K+)-adenosine triphosphatase is to antagonize the binding of K+ to its allosteric site that inhibits ouabain binding. The data support the hypothesis that ouabain binds rapidly to a K+-insensitive form of phosphorylenzyme or to its dephosphorylated analog and dissociates rapidly from E1.
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PMID:Ouabain binding to brain (Na+,K+)-adenosine triphosphatase: interactions of K+, ethanol and norepinephrine with high- and low-affinity binding. 302 3

We studied the effects of norepinephrine on solute transport and oxidative metabolism in proximal tubules. Norepinephrine (10(-6) M) in the bath stimulated fluid absorption (Jv) by proximal convoluted tubules from 0.76 +/- 0.10 to 1.01 +/- 0.11 nl X mm-1 X min-1 (P less than 0.001). Bicarbonate, chloride, and phosphate transport also increased in proportion to the increases in Jv. Norepinephrine increased ouabain-sensitive oxygen consumption (QO2) in suspensions of cortical tubules by 1.3 nmol X mg protein-1 X min-1 and had no effect on ouabain-insensitive QO2 or mitochondrial respiration. Na+-K+-ATPase activity in basolateral membranes prepared from cortical homogenates incubated with norepinephrine increased from 277.1 +/- 34.9 to 411.1 +/- 38.6 nmol Pi X mg protein-1 X min-1 (P less than 0.005). Norepinephrine also increased Na+-K+-ATPase activity of cortical homogenates by 72% but had no effect on Na+-K+-ATPase if added directly to purified basolateral membranes. These studies show that norepinephrine stimulates solute transport in the proximal tubule by increasing Na+-K+-ATPase activity indirectly through some component or components of the adrenergic receptor system.
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PMID:Norepinephrine increases Na+-K+-ATPase and solute transport in rabbit proximal tubules. 302 69

The in vitro effects of ethanol on C57BL/6J mouse forebrain ATPase activities were investigated in the presence and absence of norepinephrine. Three enzyme activities (Na + K-ATPase, Mg-ATPase, and low affinity Ca-ATPase) were studied in forebrain homogenates using a colorimetric assay. The effect of norepinephrine on ethanol inhibition of Sprague-Dawley rat brain Na + K-ATPase activity was examined in selected experiments for direct comparison with the results obtained using mouse brain. Ethanol (250-2000 mM) inhibited all ATPase activities in a concentration-dependent manner. In each case the IC50 was well beyond what would be a lethal concentration in vivo. Ethanol inhibition of mouse forebrain Na + K-ATPase activity was competitive with regards to K+ ion concentration, but was uncompetitive for inhibition of Mg-ATPase and Ca-ATPase activities. Norepinephrine (0.1 mM) did not sensitize mouse brain Na + K-ATPase activity to ethanol-induced inhibition. In contrast, norepinephrine sensitized rat brain Na + K-ATPase to ethanol inhibition when tested simultaneously with mouse brain under identical conditions. These results cannot be explained by differences in assay conditions and suggest that the interaction between norepinephrine and ethanol inhibition of Na + K-ATPase activity may be species specific. Norepinephrine alone stimulated mouse and rat brain Na + K-ATPase activity when assayed in imidazole buffer, but not when assayed in tris buffer. Furthermore, 0.1 mM norepinephrine slightly antagonized the inhibitory effect of ethanol on mouse brain Mg-ATPase activity, but did not affect ethanol-induced inhibition of Ca-ATPase activity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Ethanol-induced inhibition of mouse brain adenosine triphosphatase activities: lack of interaction with norepinephrine in vitro. 302 99

Rat striatal synaptosomes (P2-fraction) were subjected to lipoperoxidation by the addition of 120 microM Fe2+ and 200 microM ascorbic acid. This preparation (pretreated synaptosomes) was used to investigate the interaction of Pb2+ and Mn2+ on the uptake of tritiated catecholamines, Na+, K+-ATPase activity and malondialdehyde (MDA) formation in order to understand the mechanism of enhanced neurotoxicity by concurrent exposure to these metals. The combination of Pb2+ and Mn2+ (25 microM + 100 microM, respectively) produced a significant increase in the uptake of 3H-Dopamine only in the untreated synaptosomes. No significant effect was noted on the uptake of 3H-Norepinephrine in either pretreated or untreated synaptosomes. However, the combination of Pb2+ and Mn2+ produced a pronounced decrease in the activity of Na+, K+-ATPase, but the magnitude of the change was the sum of the individual metal effects. Metal interaction did not produce any significant change in the formation of MDA compared to the control (without addition of metals). These results indicate that Pb2+ and Mn2+ interaction may produce inhibition in the activity of transport ATPase in both the preparation of synaptosomes, with more pronounced effect of synaptosomes subjected to lipoperoxidation and these changes may be responsible for the disruption in the physiology of nerve impulse transmission.
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PMID:The combined effect of Pb2+ and Mn2+ on monoamine uptake and Na+, K+-ATPase in striatal synaptosomes. 304 Aug 46

The effect of norepinephrine on the consumption of O2 was studied in the skeletal muscle in the perfused hindlimbs of rats that had been kept at 4 degrees C for 5-25 days. 1) Basal rates of consumption of O2 and release of lactate were not affected by exposure to cold. 2) The stimulation of consumption of O2 by norepinephrine increased in the perfused hindlimbs of rats exposed to cold for 10-25 days, with a maximum stimulation at 20 days. The response to norepinephrine decreased markedly in hindlimbs perfused with propranolol or phentolamine. Phenylephrine, in the presence of 0.5 nM isoproterenol, stimulated the consumption of O2 at concentrations as low as 0.5 microM, with a maximum at 5 microM, in hindlimbs from the group exposed to cold for 20 days. 3) Ouabain inhibited the stimulation of consumption of O2 by norepinephrine. Norepinephrine caused a net release of K+ in control muscle but a net uptake of K+ by muscle from the group exposed to cold for 20 days. The results suggest that the calorigenic responsiveness to norepinephrine increases in skeletal muscle during acclimation of the rat to the cold, both alpha- and beta-adrenergic actions are involved in the calorigenic effects of norepinephrine, and the increased activity of the Na+-K+ ATPase under the influence of norepinephrine may be involved in the calorigenic action of norepinephrine on the skeletal muscle of cold-acclimated rats.
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PMID:Effect of norepinephrine on consumption of oxygen in perfused skeletal muscle from cold-exposed rats. 335 63

Calcium-independent noradrenaline release was studied in the isolated perfused rat heart under conditions of normoxia, cyanide intoxication, and ischemia. The release of endogenous noradrenaline and dihydroxyphenylglycol were determined by high-performance liquid chromatography. The release of dihydroxyphenylglycol, the main neuronal noradrenaline metabolite, was used as an indicator of the free axoplasmic amine concentration. When storage function of neuronal vesicles was disturbed by Ro 4-1284 or trimethyltin, high dihydroxyphenylglycol release was observed without concomitant overflow of noradrenaline. If, however, these agents were combined with inhibition of Na+K+-ATPase or with veratridine-induced entry of sodium into the neuron, both dihydroxyphenylglycol and noradrenaline were released. Noradrenaline release was independent of extracellular calcium and was suppressed by blockade of neuronal catecholamine uptake (uptake1), indicating nonexocytotic noradrenaline liberation from the sympathetic nerve ending. This release critically depended on two conditions: 1) increased cytoplasmic concentrations of noradrenaline within the sympathetic neuron and 2) intraneuronal sodium accumulation. Both conditions together were required to induce noradrenaline efflux across the plasma membrane using the uptake1 carrier in reverse of its normal transport direction. A disturbed energy status of the sympathetic neuron, induced by cyanide intoxication or ischemia, likewise caused calcium-independent noradrenaline release by interfering with both vesicular storage function and neuronal sodium homoeostatis. Again, release was sensitive to uptake1 blockade. Since neuronal sodium accumulation was the rate-limiting step, release was further accelerated when residual Na+,K+-ATPase activity was inhibited. Na+-H+ exchange was identified as the predominant pathway of sodium entry into the sympathetic nerve ending in ischemia, and its inhibition by amiloride and ethylisopropylamiloride markedly suppressed ischemia-induced noradrenaline release.
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PMID:Neuronal sodium homoeostatis and axoplasmic amine concentration determine calcium-independent noradrenaline release in normoxic and ischemic rat heart. 338 76

We examined the time course of K+-p-nitrophenylphosphatase and ouabain binding associated with cerebral cortex (Na+,K+)-AT-Pase after depletion of norepinephrine. Norepinephrine depletion by the norepinephrine-selective neurotoxin DSP4 initially reduced the indices of (Na+,K+)-ATPase, with a significant correlation between ouabain binding and tissue norepinephrine levels 16 h after DSP4. Tissue norepinephrine content and DMI binding rapidly declined after DSP4 and remained essentially unchanged for at least 8 weeks. By contrast, the indices of (Na+,K+)-ATPase remained low for about two weeks but then gradually increased, returning to baseline levels by 8 weeks after DSP4. These data indicate that, while usually regulated in part by exposure to norepinephrine, brain (Na+,K+)-ATPase undergoes adaptation to prolonged noradrenergic depletion.
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PMID:Brain (Na+,K+)-ATPase and noradrenergic function: recovery of enzyme activity after norepinephrine depletion. 609 36

Specific effects of various catecholamines as well as functional dependence of mitochondrial enzymes activity on catecholamine metabolism were studied. Dopamine activated cytochrome c oxidase in heart mitochondria and decreased this enzymatic activity in liver tissue. Noradrenaline and adrenaline activated cytochrome c oxidase in liver, brain and kidney tissues. The effect of dopamine on cytochrome c oxidase was prevented by activation of dopamine beta-hydroxylase. Increased activity of monoamine oxidase caused accumulation of catecholamine metabolites, which inhibited the succinate dehydrogenase activity in liver tissue and the cytochrome c oxidase activity in brain, kidney and liver tissues. In the catecholamine regulation of succinate dehydrogenase and ATPase activities in all the tissues studied as well as of cytochrome c oxidase activity in heart tissue the quinoid oxidation products were apparently involved.
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PMID:[Catecholamine metabolism and mitochondrial enzyme activity]. 612 94

Vanadate, the +5 oxidation state of vanadium, present in mammalian tissues, even in nerve tissue, and a competitive inhibitor of NaK-ATPase, significantly enhanced the release of [3H]noradrenaline evoked from rabbit isolated perfused pulmonary artery by electrical stimulation. Its effect proved to be concentration-dependent. Noradrenaline (10(-6) M) reduced the vanadate-potentiated release of [3H]noradrenaline. The effect of noradrenaline is mediated via alpha 2-adrenoceptors as evidenced by the finding that yohimbine 3 x 10(-7) M prevented its action. The effect of vanadate was dependent on external K ions. When the effect of vanadate on [3H]noradrenaline release was studied under conditions when the NaK-ATPase enzyme activity was inhibited by removal of external K for 45 min, vanadate was ineffective. This finding indicates that the effect is related to the inhibition of NaK-ATPase activity, a condition known to result in transmitter release.
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PMID:Stimulation by vanadate of [3H]noradrenaline release from rabbit pulmonary artery and its inhibition by noradrenaline. 612 38


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