Effects of barium chloride on resting and action potentials of ventricular fibers of the frog.

By means of an intracellular capillary electrode the effects of barium chloride on the resting and action potentials of ventricular fibers of the frog were recorded in hearts with circulation intact and hearts isolated and perfused. The changes were essentially similar in both preparations. The major change observed was a statistically significant (p < 0.01) increase in duration of the action potential. Changes were also observed in the magnitude of the resting andaction potential, in the rateof depolarization, and in rhythm, but these did not occur invariably. By a series of exclusion experiments it was demonstrated that barium lias a direct effect on the ventricular fibers of the frog's heart.