Effect of monovalent cations on the ouabain inhibition of the sodium and potassium ion activated adenosine triphosphatase

Barnett, Ronald E.

doi:10.1021/bi00826a004

Cited by 139 publications

(35 citation statements)

References 26 publications

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“…P-conformation of the Na-K-ATPase. Since the binding and unbinding of K is probably extremely fast (Glynn & Richards, 1982) (Barnett, 1970;Lindenmayer & Schwartz, 1973;Inagaki, Lindenmayer & Schwartz, 1974, Sachs, 1974Kropp & Sachs, 1977;Hobbs & Dunham, 1978). The main difference between the various schemes concerns the form of the phosphoenzyme to which cardiac glycosides are assumed to bind.…”

Section: Discussionmentioning

confidence: 99%

Inhibition of the sodium pump in guinea‐pig ventricular muscle by dihydro‐ouabain: effects of external potassium and sodium.

Daut¹

1983

The Journal of Physiology

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SUMMARY1. The inhibition of the electrogenic pump current in quiescent guinea-pig ventricular muscle by dihydro-ouabain (DHO) was studied with the three-micro-electrode voltage-clamp technique described previously (Daut, 1982 c). From dose-response curves of the drug-induced current change (ID) the equilibrium dissociation constant of the binding of DHO to the Na-K pump (KD) and the electrogenic pump current flowing in the steady state (Ip) were inferred (Daut & Riidel, 1982b 6. The external Na concentration ([Na]0) was varied between 147 and 49 mM (substituted by choline or Tris). Reduction of [Na]o produced a proportional decrease of Ip. This may be a consequence of the accompanying reduction of passive Na influx and the resulting decrease in intracellular Na activity (ai a).7. Reduction of [Na]o markedly increased KD. This effect may be mediated by competition between Na and K at the K-loading sites of the pump and/or by separate modulatory Na-binding sites.8. It is concluded that the well known effects of external Na and K on the positive inotropic action of cardiac glycosides can be fully accounted for by the marked changes in the apparent binding affinity of the drug reported here.

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Section: Discussionmentioning

confidence: 99%

Inhibition of the sodium pump in guinea‐pig ventricular muscle by dihydro‐ouabain: effects of external potassium and sodium.

Daut¹

1983

The Journal of Physiology

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“…Assay of Na ϩ /K ϩ -ATPase Activity-Enzyme activity was measured by monitoring the hydrolysis of ATP to ADP using the coupled assay of Barnett (14). Oxidation of NADH to NAD ϩ was followed on a Beckman DU 640 spectrophotometer at a wavelength of 340 nm.…”

Section: Methodsmentioning

confidence: 99%

Role of Serine/Threonine Protein Phosphatases in Insulin Regulation of Na+/K+-ATPase Activity in Cultured Rat Skeletal Muscle Cells

Ragolia¹,

Cherpalis²,

Srinivasan³

et al. 1997

Journal of Biological Chemistry

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“…Malate dehydrogenase (Stams et al 1984) and ATPase (Barnett 1970) activities were determined in spectrophotometric assays by monitoring the absorbance at 340 nm. Quinone concentration was determined by the spectrphotometic NBT/glycinate redox assay (Fluckiger et al 1995) with authentic PQQ used as the standard.…”

Section: Other Assaysmentioning

confidence: 99%

In vitro studies indicate a quinone is involved in bacterial Mn(II) oxidation

Johnson

Tebo

2007

Arch Microbiol

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Manganese(II)-oxidizing bacteria play an integral role in the cycling of Mn as well as other metals and organics. Prior work with Mn(II)-oxidizing bacteria suggested that Mn(II) oxidation involves a multicopper oxidase, but whether this enzyme directly catalyzes Mn(II) oxidation is unknown. For a clearer understanding of Mn(II) oxidation, we have undertaken biochemical studies in the model marine α-proteobacterium, Erythrobacter sp. strain SD21. The optimum pH for Mn(II)-oxidizing activity was 8.0 with a specific activity of 2.5 nmol × min −1 × mg −1 and a K m = 204 µM. The activity was soluble suggesting a cytoplasmic or periplasmic protein. Mn(III) was an intermediate in the oxidation of Mn(II) and likely the primary product of enzymatic oxidation. The activity was stimulated by pyrroloquinoline quinone (PQQ), NAD + , and calcium but not by copper. In addition, PQQ rescued Pseudomonas putida MnB1 non Mn(II)-oxidizing mutants with insertions in the anthranilate synthase gene. The substrate and product of anthranilate synthase are intermediates in various quinone biosyntheses. Partially purified Mn(II) oxidase was enriched in quinones and had a UV/VIS absorption spectrum similar to a known quinone requiring enzyme but not to multicopper oxidases. These studies suggest that quinones may play an integral role in bacterial Mn(II) oxidation.

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Effect of monovalent cations on the ouabain inhibition of the sodium and potassium ion activated adenosine triphosphatase

Cited by 139 publications

References 26 publications

Inhibition of the sodium pump in guinea‐pig ventricular muscle by dihydro‐ouabain: effects of external potassium and sodium.

Inhibition of the sodium pump in guinea‐pig ventricular muscle by dihydro‐ouabain: effects of external potassium and sodium.

Role of Serine/Threonine Protein Phosphatases in Insulin Regulation of Na+/K+-ATPase Activity in Cultured Rat Skeletal Muscle Cells

In vitro studies indicate a quinone is involved in bacterial Mn(II) oxidation

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