Effect of potassium and norepinephrine on the tone of the isolated artery: Changes by ouabain pretreatment

Zusammenfassung Vorbehandlung von Arterienstreifen mit g-Strophantin (>10^–8 g/ml) kehrt die mechanische Reaktion auf K⁺-Änderungen im Bereich von 1 bis 10 mM KCl, nicht aber die K⁺-Wirkung auf die Kontraktion durch Noradrenalin oder Barium um. Danach könnte die K⁺-Dilatation der Arterien auf der Aktivierung einer elektrogenen Na⁺-Pumpe beruhen.

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The authors gratefully acknowledge the technical assistance by Mrs.B. Heinemann.     

Inhibition of potassium (86Rb) influx in Ehrlich ascites cells by bilirubin and ouabain

Summary Bilirubin inhibited influx of potassium into Ehrlich ascites cells without altering efflux. The data showed that compared with ouabain, net potassium influx components were impaired in a higher degree by bilirubin. The reversal of this effect was shown, in our experimental conditions, only for ouabain.Acknowledgments. This work was supported by a grant from the Consejo Nacional de Investigaciones Cientificas y Técnicas, República Argentina. The authors wish to thank Miss Marta S. Göthje for techical assistance.     

Effect of ouabain on volume regulation of rabbit kidney cortex slices in hypo-osmotic media

Summary The volume regulation process at work in rabbit kidney cortex slices submitted to hypo-osmotic media show both a swelling limitation and a volume readjustment phase. Swelling limitation is Na⁺ dependent and is blocked by ouabain 10^–3 M. There is, however, no need to implicate the activity of a ouabain sensitive Na⁺/K⁺ pump in this process.This work has been aided by a grant 1.5.422.82F from the FNRS to R.G. We wish to thank Mr J.M. Theate for his skilful assitance.     

Toxicity of ouabain on Drosophila melanogaster

Summary Ouabain, also called g-strophantin, is an inhibitor of the Na⁺/K⁺-activated plasma membrane ATPase. Treatment of Drosophila melanogaster with 3–6 mM of this substance leads to a markedly reduced survival of the flies.     

Effect of ouabain on volume regulation of rabbit kidney cortex slices in hypo-osmotic media

The volume regulation process at work in rabbit kidney cortex slices submitted to hypo-osmotic media show both a swelling limitation and a volume readjustment phase. Swelling limitation is Na+ dependent and is blocked by ouabain 10(-3) M. There is, however, no need to implicate the activity of a ouabain sensitive Na+ /K+ pump in this process.     

The effect of intracellular potassium ions on active sodium efflux in frog sartorius muscle

Zusammenfassung Radioaktive Untersuchungen zeigen. dass intrazelluläre K⁺-Ionen den aktiven Na⁺-Austausch hemmen.     

The activation of membrane ATPase by ouabain in several tissues of the golden hamster (Mesocricetus auratus) in the absence of potassium

Summary The activity of the membrane ATPase of 5 organs of the golden hamster was increased by 10^–7–10^–3 moles/l ouabain in K⁺-free medium. In similar experiments on rats no increase was observed.     

Effect of pH on active sodium excretion

Zusammenfassung Die aktive Na-Ausscheidung Nareicher quergestreifter Muskeln konnte durch eine mässige Steigerung der Wasserstoffionekonzentration gehemmt werden. Obgleich der intensivere Kohlehydratstoffwechsel an und für sich die Na-Abgabe steigert, wurde dieser Effekt durch die Herabsetzung des pH unterdrückt.

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On leave from Department of Urology, University of Medicine, Budapest (Hungary).     

The effect of ouabain on water consumption in the rat

Résumé L'ouabain diminue la consommation d'eau, stimulée par l'injection d'une solution sallée hypertonique, chez les rats normaux ou néphrectomisés.     

Effect of temperature and concentration on the anomalous potassium uptake of thermophilic plants

Zusammenfassung Nachweis, dass in der thermophilen Gurke (Cucumis sativus) ein mehrphasiges K⁺-Aufnahme-system existiert, welches sich von jenem kälteunempfindlicher Pflanzen unterscheidet. Untersucht wurden abgetrennte Gurkenwurzeln im Temperaturbereich von 0 und 21 °C.     

Effect of insulin on potassium transfer in human and chicken erythrocytes

Riassunto La conservazione al freddo degli eritrociti umani e di pollo per 6 giorni causa una fuoruscita di potassio dai globuli. Parte del potassio rientra nelle cellule durante incubazione a 37° C.La uabaina blocca questo fenomeno. L'insulina non ha effetto significativo nè sull'assunzione di potassio da parte del globulo rosso, nè sull'azione bloccante della uabaina.

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Aided by a grant from the Chicago Heart Association.

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Trainee, Diabetes Teaching Grant No. 2A-5102, National Institute of Arthritis and Metabolic Diseases, Public Health Service.     

Effect of potassium on isolated bovine facial and human saphenous veins

Summary A moderate elevation of external (K ₀ ⁺ ) (5–10 mM) induces relaxation in bovine facial and human saphenous veins. A further increase of (K ₀ ⁺ ) leads to biphasic reactions (relaxation followed by contraction). Concentrations of (K ₀ ⁺ ) higher than about 15 mM cause contractions only. The potassium-induced relaxation may be explained by the stimulation of an electrogenic sodium pump.