[Effect of quinine on the calcium currents of mollusk neurons].

The effects of quinine on the peak amplitude and relaxation of calcium current (ICa) were examined on isolated unidentified snail neurons. Quinine (1 X 10(-5)-5 X 10(-4) mol/l) reversibly slowed the relaxation of ICa in a dose-dependent manner (early effect) and suppressed the peak amplitude of ICa in a dose-dependent and time-dependent manner (delayed effect). Quinine induced a shift of the current-voltage relationship for peak ICa by 5-10 mV in the hyperpolarizing direction. A half inhibition of ICa peak amplitude was induced by 6 X 10(-5) mol/l quinine. The results show that quinine is an effective inhibitor of calcium channels in snail neurons.