Evidence against a role of (Na++K+-ATPase in the alpha-adrenoceptor mediated positive inotropic effect of phenylephrine

Summary Phenylephrine (0.1–100 M) in the presence of 1 M propranolol increased the force of contraction in electrically driven papillary muscles from cats. This presumably alpha-adrenoceptor mediated positive inotropic effect of phenylephrine occurred without any influence on (Na⁺+K⁺-ATPase activity.This work was supported by the Deutsche Forschungsgemeinschaft.     

The effect of temperature on Ca2+ uptake and Ca2+-activated ATP hydrolysis by cardiac sarcoplasmic reticulum

Zusammenfassung Der Ca²⁺-Transport und die Ca²⁺-aktivierte ATP Hydrolyse (ATP extra Spaltung) durch Membranen des cardialen sarkoplasmatischen Retikulums zeigen die gleiche Temperaturabhängigkeit. Die Aktivierungsenergie der Ca²⁺-Aufnahme und der ATP extra Spaltung, gemessen bei Anwesenheit von Oxalat, beträgt 16.65±0.87 und 17.93±0.49 Kcal/Mol^–1.     

The effect of adrenaline on the electrogenic Na+ pump in cardiac muscle cells

Electrogenic Na+ pump currents during K+-activated hyperpolarizations of bullfrog atrium muscle fibres are increased by adrenaline. The log dose-response relation between these currents and activating K+ concentrations is expressed by a sigmoidal curve, which is shifted in parallel to the left by adrenaline. It is suggested that adrenaline increases the rate of Na+ extrusion without increasing the Na/K coupling ratio and total number of pumping sites.     

Influence of Cu++ and Zn++ ions on the effects of ethyl methanesulfonate (EMS) on chromosomes

Résumé La capacité de l'EMS de casser les chromosomes n'existe que lorsque des ions ont été ajoutés pendant les traitements. A ce point de vue, Cu⁺⁺ et Zn⁺⁺ se révèlent très efficaces. Cette réaction dépend du pH et varie avec la concentration ionique et la concentration d'EMS. On donne une explication probable de ces faits.     

The influence of oestradiol-17β on the rat uterine Na+, K+-Mg++ activated adenosine triphosphatase activity

Zusammenfassung 17--Östradiol wirkt am Rattenuterus hemmend auf die ATPase, von der bekannt ist, dass sie auf die sogenannte Natriumpumpe in der Zelle wirkt.     

A histochemical demonstration of the Na++K+-ATPase activity in the thyroid and the effect of cyclic adenosine monophosphate (c-AMP)

Summary With a suitable modification of the Farquhar and Palade technique the Na⁺+K⁺-ATPase activity in guineapig thyroid is demonstrated. The addition of c-AMP (5×10^–6 M or 1.5×10^–5 M) to the incubation media produced an apparent intensification of the Na⁺+K⁺-ATPase activity in the thyroid.This work was supported by a grant from ZMNU of Serbia.     

Further data on the evaluation of platelet Ac-globulin and its plasmatic origin

Zusammenfassung Die Eigenschaften des Plättchen-Ac-Globulins wurden mit Rücksicht auf die Thromboplastinbildung untersucht.     

Experiments on the mechanism of the inhibition of mitochondrial Ca2+ transport by La3+ and ruthenium red

Summary The effects of La³⁺ and ruthenium red on the energy-linked uptake of Ca²⁺ mediated by a synthetic neutral Ca²⁺ ionophore have been investigated in rat liver mitochondria. The results indicate that unspecific surface charge effects do not play a major role in the mechanism of inhibition of mitochondrial Ca²⁺ transport by La³⁺ and ruthenium red.Acknowledgments. The authors are indebted to Prof. W. Simon, ETH Zurich, for having provided samples of the synthetic neutral Ca²⁺ ligand, and to M. Mattenberger for the valuable technical assistence. The work was supported by a grant of the Swiss Nationalfonds (grant No. 3.1720.75).     

Effects of inhibition and stimulation of Na+-K+ active transport on the resting membrane input conductance of the guinea-pig ventricle

The effects of inhibition by ouabain and stimulation by high frequency drive of the sarcolemmal Na+-K+ active transport system on the resting input conductance (gi) of guinea-pig ventricular muscles were determined. Although both pump inhibition and stimulation were associated with changes in electrophysiological properties of the muscles, neither had a significant effect on gi.