POTASSIUM CHANNEL OPENERS AND VASCULAR SMOOTH-MUSCLE RELAXATION

Potassium channel openers comprise a diverse group of chemical agents which open plasmalemmal K-channels. They show selectivity for smooth muscle, although K-channels in cardiac and skeletal muscle, neurones and the pancreatic β-cell are also affected at relatively high concentrations. In addition, at least one endogeneous K-channel opener of vascular origin-endothelium-derived hyperpolarizing factor-exists and in man plays a role in modulating blood vessel tone. The type of K-channel involved in the actions of both exogenous and endogenous K-channel openers is still uncertain, although a prime candidate in smooth muscle seems similar to the [ATPi]-modulated K-channel in the pancreatic β-cell. This review focuses attention on the action of these agents in vascular smooth muscle and on the possible clinical exploitation of their powerful vasorelaxant properties. © 1990.