Electrophysiological effects of methyl 3-O-methyl gallate on single muscle fibres

The electrophysiological changes induced by methyl 3-O-methyl gallate, a substance extracted from Crinodendron hookerianum, have been studied on 32 muscle fibres of Pleurodema thaul. Four concentrations were used: 1 x 10(-5), 2 x 10(-5), 1 x 10(-4), and 2 x 10(-4) mol/l, the results being a reversible dose-dependent reduction of the overshoot and the amplitude of the action potential, a prolongation of the rise and decay times of the spike, as well as a depolarization of the resting membrane potential. An explanation of these results by a blockade of the potassium and possibly the sodium channels in the cellular membrane is discussed.