Effects of 4-aminopyridine on pacemaker activity of frog sinus venosus

Abstract

The effects of low concentrations of 4-aminopyridine (4-AP) were studied on the frog sinus venosus by means of intracellular microelectrodes. 4-AP depressed spontaneous automaticity. This effect was not reversed by atropine. 4-AP also prolonged the sinus action potential repolarization and slowed the rate of diastolic depolarization. These effects are attributed to blockade of potassium conductance. © 1980.