EFFECTS OF POTASSIUM CHANNEL OPENERS IN ISOLATED HUMAN CEREBRAL-ARTERIES

THE OBJECTIVE OF this study was to compare the relaxant effects of the K+ channel openers pinacidil and lemakalim in isolated human pial art eries with the effects of the dihydropyridines nifedipine and nimodipi ne and the prostacyclin analog iloprost. Relaxation was measured in ve ssels contracted by 40 mmol/L K+. In contrast to the potent and consis tent relaxant effects of nifedipine, nimodipine, and iloprost, the pot ency of pinacidil and lemakalim proved to be highly variable and inver sely correlated with the onset velocity of the preceding contractions of K+ as well as with the endothelium-dependent relaxation of carbacho l. Thus, in contrast to dihydropyridines and iloprost, pinacidil and l emakalim selectively elicited potent relaxations in those arteries tha t exhibited signs of altered vascular wall functions.