ATP-dependent potassium channels contribute to motor regulation of esophageal striated muscle in rats

The aim of the present study was to clarify roles of ATP-dependent potassium channels (K(ATP) channels) in motility of the striated muscle portion in the esophagus. An isolated segment of the rat esophagus was placed in an organ bath and mechanical responses were recorded using a force transducer. Electrical stimulation of the vagus nerve evoked contractile response of striated muscle in the esophageal segment. Application of glibenclamide, an antagonist of K(ATP) channels, increased amplitude of vagally mediated twitch contractions of the rat esophagus. On the other hand, minoxidil, an agonist of K(ATP) channels, decreased amplitude of twitch contractions. RT-PCR revealed the expression of subunits of K(ATP) channels in esophageal tissue. In addition, immunopositivity for subunits of K(ATP) channels was observed in the striated muscle cells of the esophageal muscle layer. These findings indicate that K(ATP) channels contribute to motor regulation of striated muscle in the rat esophagus.