| Abstract: | Under voltage clamp conditions ionic currents of neurons of the molluskHelix were studied in solutions containing barium ions. Replacement of the calcium ions in the normal external solution by barium ions led to displacement of the potassium conductivity versus membrane potential curve along the voltage axis toward more positive potentials and also to a decrease in the limiting value of the potassium conductance of the membrane. In sodium- and calcium-free solutions containing barium ions two fractions of the inward current are recorded: quickly (I) and slowly (II) inactivated. The rates of activation of these fractions are comparable. Barium ions are regarded as carriers of both fractions of the inward current. It is postulated that both fractions of the barium current are carried along the calcium channels of the membrane.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 9, No. 4, pp. 408–414, July–August, 1977. |
