Relationship Between Potassium and Vagal Action on Atrioventricular Transmission

Abstract

The relationship between the effects of potassium and vagal stimulation on transmission through the atrioventricular transmission system was investigated. It was observed that infusion of isotonic potassium chloride alleviated atrioventricular block induced by vagal activity. This occurred at plasma potassium levels ranging from 4.8 to 6.9 mEq/liter. This antagonism does not appear to be mediated by catecholamine release since infusion of epinephrine (0.23 µg/min) did not relieve the block. At plasma levels higher than those capable of inhibiting vagal action, potassium enhances parasympathomimetic actions on A-V transmission and, at still higher levels, potassium is capable of inducing A-V block which is independent of the vagus.