Abstract
Effects of sodium nitroprusside, 8-bromo cGMP and methylene blue on the glibenclamidesensitive K+ current evoked by K+ channel openers in Xenopus oocytes were studied. Sodium nitroprusside (0.1-1 mM, an activator of guanylate cyclase)enhanced by 20-50% the K+ currents induced by KRN2391, nicorandil and cromakalim (K+ channel openers). 8-Bromo cGMP (1 mM)also increased the K+ current by 40-60%. Methylene blue (10 μM, an inhibitor of guanylate cyclase)irreversibly blocked the K+ current by about 20-30%. These results suggest that the activation of glibenclamide-sensitive K+ channels by K+ channel openers is modulated either positively or negatively by intracellular cGMP in oocytes.
