(+)-Tubocurarine blocks the Ca 2+-dependent K +-channel of the bullfrog sympathetic ganglion cell

Abstract

(+)-Tubocurarine ((+)-Tc:10–100 μM) reduced the duration of the afterhyperpolarization, which was induced by the activation of Ca 2+-dependent K +-conductance (G K,Ca) following an action potential in the bullfrog sympathetic ganglion cell, but did not affect the maximum rates of rise and fall of Na +- and Ca 2+-dependent action potentials. The amplitudes of slow rhythmic membrane hyperpolarizations produced by rhythmic rises in the G K,Ca were also decreased by (+)-Tc without a change in their intervals. Thus, (+)-Tc appears to block the Ca 2+-dependent K +-channel of the bullfrog sympathetic ganglion cell.