Humoral and cellular effects of the K(+)-channel activator cromakalim in man.

The effect of cromakalim, a K(+)-channel activator, on the plasma renin-angiotensin-aldosterone system, catecholamines and alpha-atrial natriuretic peptide, and on the intraerythrocyte concentration and transmembrane fluxes of Na+ and K+ has been investigated in 18 normal male subjects, in a double-blind parallel study. After a run-in period on placebo for 1 week, the subjects were treated either with placebo (n = 6) or cromakalim (n = 12) for 1 week. Plasma renin activity was significantly increased during cromakalim. No effect of cromakalim on plasma angiotensin II, aldosterone, adrenaline, noradrenaline and alpha-atrial natriuretic peptide was demonstrated. The intra-erythrocyte K+ concentration was decreased during cromakalim administration and Ca2(+)-dependent K(+)-channels in red blood cells were increased.