Effects of the KATP channel opener bimakalim on coronary blood flow, monophasic action potential duration, and infarct size in dogs.

BACKGROUNDThe major purpose of the present study was to determine the effect of the potassium channel opener bimakalim, administered intracoronary only during the initial 10 minutes of ischemia, on myocardial infarct size in anesthetized dogs. A second aim was to test the possibility that bimakalim mediates its cardioprotective effects by accelerating the rate of myocyte action potential shortening during early ischemia. A third aim was to determine the relative potency of bimakalim to open coronary vascular ATP-regulated potassium (KATP) channels versus myocyte KATP channels.METHODS AND RESULTSBarbital-anesthetized open-chest dogs were used. In the initial studies, bimakalim (0.1 to 10 micrograms/min) was infused into the left anterior descending coronary artery (LAD), and changes in coronary blood flow and monophasic action potential duration (MAPD) were used as indexes of coronary vascular KATP channel and myocyte KATP channel activity, respectively. In subsequent infarct studies, dogs were subjected t...