Blockade of the ATP-Sensitive Potassium Channel Modulates Reactive Hyperemia in the Canine Coronary Circulation

The mechanism of reactive hyperemia remains unknown. We hypothesized that reactive hyperemia was related to the opening of ATP-sensitive potassium channels during coronary occlusion. The resulting hyperpolarization of the smooth muscle cell plasma membrane might reduce calcium influx through voltage-dependent calcium channels and result in relaxation of smooth muscle tone and vasodilation. In eight open-chest, anesthetized dogs, 30-second coronary occlusions resulted in an average flow debt repayment of 200±41%. After low-dose (0.8 μmol/min) and high-dose (3.7 μmol/min) infusion of intracoronary glibenclamide, flow debt repayment fell to 76±14% and 50±8%, respectively (p