Vasorelaxant effects of the potassium channel opener SR 47063 on the isolated human saphenous vein and rat aorta.

The vasorelaxant effects of SR 47063 (4-(2-cyanimino-1, 2-dihydropyrid-1-yl)-2,2-dimethyl-6-nitr ochromene), a new K(+)-channel opener structurally related to levcromakalim, were examined in isolated human saphenous vein (HSV) and rat aorta (RA). HSV or RA rings were precontracted with either KCl or noradrenaline and cumulative relaxant concentration-response curves were obtained for SR 47063 (0.1 nM to 1 microM) in the presence or absence of 3 microM glibenclamide. SR 47063 potently relaxed HSV and RA precontracted with 20 mM (but not 60 mM) KCl or 10 microM noradrenaline in a concentration-dependent manner, showing slightly greater activity in the aorta. The potency of the effect of SR 47063 on HSV and RA was 12- and 58-fold greater, respectively, than that reported for the structurally related K(+)-channel opener levcromakalim. The vasorelaxant action of SR 47063 in both blood vessels was strongly inhibited by 3 microM glibenclamide, consistent with a mechanism of action involving ATP-dependent K(+)-channels.