Effect of cromakalim on smooth muscle cells of guinea-pig taenia caeci.

Cromakalim caused hyperpolarization and reduction of the electrotonic potential in a concentration-dependent manner in smooth muscle cells of guinea-pig taenia caeci. There was a relatively constant change in the electrotonic potential under calcium-free, low-sodium and low-chloride conditions in the presence of cromakalim as compared to control conditions with Krebs solutiuon. The effect of cromakalin (10(-5) M) was inhibited by glibenclamide (5 X 10(-5) M). These results indicate that cromakalim specifically promotes potassium efflux in smooth muscle cells of the guinea-pig taenia caeci via glibenclamide-sensitive potassium channels, to cause hyperpolarization, suppression of spike activity and relaxation.