Effects of octylguanidine on the electrical activity of Xenopus heart.

The effects of laboratory synthesized octylguanidine are described. There is an early decease of the maximum rate of rise of the action potential with negligible reduction of the overshoot although the membrane resting potential is unchanged. Subsequently, there is a remarkable reduction of both membrane potential and overshoot, while the plateau is shortened. The former effects resemble those seen with tetrodotoxin, the latter ones, with metabolic poisons.