Functional Significance of the Effects of Neurotransmitters on the Na<sup>+</sup>,K<sup>+</sup>‐ATPase System

Kometiani, Zurab; Tsakadze, Leila; Jariashvili, Tamar

doi:10.1111/j.1471-4159.1984.tb02779.x

Cited by 23 publications

(6 citation statements)

References 11 publications

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“…In accordance with the data reported (Robinson and Flasher 1979; Kometiani et al 1984), the presence of only one catalytic site per α-subunit has been identified for the Na, K-ATPase system. Therefore, the molecule has a dimeric nature with two identical subunits, 2(αβ), that must be a universal system for all P-type transport ATPases.…”

Section: Discussionsupporting

confidence: 90%

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Cl Anion-Dependent Mg-ATPase

et al. 2012

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We studied, in the rat brain, the synaptosomal and microsomal membrane fractions of Cl− ion-activated, Mg2+-dependent ATPase, satisfying the necessary kinetic peculiarities of transport ATPases, by a novel method of kinetic analysis of the multisite enzyme systems: (1) the [Mg-ATP] complex constitutes the substrate of the enzymic reaction; (2) the V = f(Cl−) dependence-reflecting curve is bell-shaped; (3) substrate dependence, V = f(S), curves at a constant concentration of free ligands (Mgf, ATPf, Cl−); (4) as known from the literature, in the process of reaction a phosphorylated intermediate is formed (Gerencser, Crit Rev Biochem Mol Biol 31:303–337, 1996). We report on the Cl-ATPase molecular mechanism and its place in the “P-type ATPase” classification.

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Section: Discussionsupporting

confidence: 90%

“…In the Cl-ATPase study we applied kinetic analysis of multisited enzyme systems (Kometiani et al 1984), which is a single method used from kinetic investigation of multisited enzyme systems.…”

Section: Methodsmentioning

confidence: 99%

Cl Anion-Dependent Mg-ATPase

et al. 2012

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“…In previous studies, Kometiani et al (1984) have reported inhibition of the Na +/K+-ATPase by acetylcholine only in cholinergic synaptosomal membranes. No effect of ace@choline on Na+/K÷-ATPase was seen in membranes from liver, kidney, red cell ghosts and adrenergic synaptosomes.…”

Section: Discussionmentioning

confidence: 99%

Evidence against a regulation of Na+/K+-ATPase by Gi proteins. Failure to detect an influence of G proteins on Na+/Ca2+-exchange in cardiac sarcolemmal membranes

Mura

Zeifang

Piacentini

et al. 1996

Naunyn-Schmiedeberg's Arch Pharmacol

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In the myocardium the inhibitory guanine nucleotide-binding regulatory proteins (Gi proteins) mediate negative chronotropic and negative inotropic effects by activation of K+ channels and inhibition of adenylyl cyclase. The concept of a uniform inhibitory action of Gi proteins on myocardial cellular activity has been questioned by the recent observations of adenosine-induced activation of the Na+/Ca(2+) exchange and a carbachol-induced inhibition of the Na+/K(+)-ATPase activity in cardiac sarcolemmal membranes. The aim of the present study, therefore, was to reinvestigate the putative regulation of Na+/Ca(2+) exchange and Na+/K(+)-ATPase activity in purified canine sarcolemmal membranes. These membranes were enriched in adenosine A1 (Maximum number of receptors, Bmax 0.033 pmol/mg) and muscarinic M2 (Bmax 2.9 pmol/mg) receptors and contained Gi2 and Gi3, two Gi protein isoforms, and G0, another pertussis toxin-sensitive G protein, as detected with specific antibodies. The adenosine A1-selective agonist, (-)-N6-(2-phenylisopropyl)-adenosine, and the muscarinic agonist, carbachol, both inhibited isoprenaline-stimulated adenylyl cyclase activity by 25% and 35% respectively, and the stable GTP analogue 5'-guanylylimidodiphosphate inhibited forskolin-stimulated adenylyl cyclase activity by 35% in these membranes. The characteristics of Na+/Ca(2+) exchange and Na+/K(+)-ATPase activity as well as those of the ouabain-sensitive, K(+)-activated 4-nitrophenylphosphatase, an ATP-independent, partial reaction of the Na+/K(+)-ATPase, were in agreement with published data with regard to specific activity, time course of activity and substrate dependency. However, none of these activities were influenced by adenosine, (-)-N6-(2-phenylisopropyl)-adenosine, carbachol, or stable GTP analogs, suggesting that Na+/Ca(2+) exchange and Na+/K(+)-ATPase are not regulated by Gi proteins in canine cardiac sarcolemmal membranes.

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“…There arise many questions and one of them is the problem of participation of Ca 2+ ions [ 5 , 6 ]. Ca 2+ ion and EGTA are modifiers of the Na/K-ATPase system and at the same time EGTA sharply attenuates the inhibition of Na/K-ATPase by NA [ 2 ]. Therefore arises a necessity to clarify the role of Ca 2+ ions in the mechanism of action of NA and SF on the Na/K-ATPase system.…”

Section: Introductionmentioning

confidence: 99%

The effect of EGTA and Ca++ in regulation of the brain Na/K-ATP-ase by noradrenaline

2001

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Background The Na/K-ATPase activity of the brain synaptic plasma membranes (SPM) is regulated by noradrenaline (NA) and the synaptosomal factor SF (soluble protein obtained from the synaptosome cytosol). In the absence of SF, NA inhibits Na/K-ATPase, while, on addition of SF to the reaction medium, there is a NA-dependent activation of Na/K-ATPase . On the other hand, EGTA augments the Na/K-ATPase activity and attenuates the ability of NA to inhibit Na/K-ATPase. Results Considering that Ca 2+ ion is a Na/K-ATPase modifier, it can be assumed that the effect of NA and SF is a Ca 2+ -dependent process. However, in the presence of 0.3 mM EGTA and 0.1 mM NA, the apparent inhibition constant for Ca 2+ (at [Ca 2+ ] > 0.3 mM) is not SF dependent, while the apparent activation constant for SF does not change at increasing Ca 2+ concentration ([Ca 2+ ] < 0.3 mM). At various Ca 2+ concentrations (0.06, 0.35 and 0.6 mM), no significant changes occur in the mode of action of NA on the Na/K-ATPase activity in the presence of 5 μg/ml SF. EGTA also has no effect on the NA-independent activation of Na/K-ATPase evoked by high SF concentrations. Conclusions Taking into account that in the absence of EGTA similar results have been obtained, it can be concluded that the effect of NA and SF on brain Na/K-ATPase is a Ca 2+ -independent process.

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Functional Significance of the Effects of Neurotransmitters on the Na⁺,K⁺‐ATPase System

Cited by 23 publications

References 11 publications

Cl Anion-Dependent Mg-ATPase

Cl Anion-Dependent Mg-ATPase

Evidence against a regulation of Na+/K+-ATPase by Gi proteins. Failure to detect an influence of G proteins on Na+/Ca2+-exchange in cardiac sarcolemmal membranes

The effect of EGTA and Ca++ in regulation of the brain Na/K-ATP-ase by noradrenaline

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Functional Significance of the Effects of Neurotransmitters on the Na+,K+‐ATPase System

Cited by 23 publications

References 11 publications

Cl Anion-Dependent Mg-ATPase

Cl Anion-Dependent Mg-ATPase

Evidence against a regulation of Na+/K+-ATPase by Gi proteins. Failure to detect an influence of G proteins on Na+/Ca2+-exchange in cardiac sarcolemmal membranes

The effect of EGTA and Ca++ in regulation of the brain Na/K-ATP-ase by noradrenaline

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Functional Significance of the Effects of Neurotransmitters on the Na⁺,K⁺‐ATPase System