[Relation of Ca2+ efflux from the heart to the concentration of Ca-channel blockers]. / Zavisimost' vykhoda Ca2+ iz serdtsa ot kontsentratsii blokatorov Ca-kanalov.

Dependence of calcium ion efflux from the heart ventricles on the concentration of verapamil, fenigidine and nicardipine was studied in frogs, using Ca-sensitive electrodes. The effect of sodium and potassium ions was also investigated. It was established that dependence of calcium ion efflux (delta Ca2+) on the concentration of Ca-antagonists (B) may be expressed by the following formula: (Formula: see text). With cellular membrane depolarization 50 mM KCl, none of the blockers (10(-5) M) caused Ca2+ efflux from ventricular cells. Analogous phenomenon was noted in low-sodium solution (60 mM).

[Relationship between incurrent flow, calcium ion concentration and membrane potential]. / Zavisimost' vkhodiashchego toka ot kontsentratsii ionov kal'tsiia i membrannogo potentsiala.

A dependence of the inward current across the cell membrane giant neurones at garden snail was investigated under voltage champ. It has been concluded that there are two components of the inward current: a calcium-dependent and I0. The latter current probably was carried by sodium ions. The inward Ca current (ICa) is then given as a function [Ca]2+ by: formula (see text) : KCa is a dissociation constant of the sites in outer part channel independent of membrane voltage. The experimental data are interpreted by two barrier membrane model bases of absolute reaction rate Eyring's theory.