Glibenclamide Specifically Blocks ATP-Sensitive K⁺ Channel Current in Atrial Myocytes of Guinea Pig Heart

Abstract

Effects of glibenclamide on the control membrane ionic currents, acetylcholine or adenosine-induced K⁺ current, and nicorandil-induced K⁺ current were examined in single atrial myocytes of guinea pig heart. The nystatin-whole cell clamp technique was used. Nicorandil evoked the time-independent K⁺ current which is probably the current through the ATP-sensitive K⁺ channel. Glibenclamide inhibited this current in a concentration-dependent fashion, although it had no effect on the other currents. We concluded that glibenclamide specifically inhibits the ATP-sensitive K⁺ channel current in cardiac myocytes.