Effect of quinidine and pronethalol on acetylstrophanthidin-induced ventricular arrhythmia in cats treated with reserpine.

With pronethalol, quinidine, and reserpine it was necessary to increase the dose of acetylstrophanthidin which produced arrhythmia in combination with vagal stimulation. However, in reserpine-treated animals, quinidine and pronethalol were ineffective. The capability of large doses of acetylstrophanthidin to produce ventricular arrhythmia was not diminished by quinidine, pronethalol, or reserpine. While pronethalol decreased the S-A nodal rate in normal animals, it failed to produce an effect on rate after reserpine pretreatment. Since after catecholamine depletion by reserpine, pronethalol and quinidine did not affect acetylstrophanthidin-induced ventricular arrhythmia, it is suggested that the antidigitalis effect of these agents is related to their actions to diminish adrenergic nervous activity. ADDITIONAL