Femoral Vasodilation to Cromakalim is Blocked by U37883A,a Non-sulphonylurea that Selectively Inhibits KATP Channels

The purpose of the present study was to determine the effects of U37883A, a non-sulphonylurea inhibitor of K_ATP channels, in the femoral vascular bed of the anaesthetized dog. Administration of U37883A, 4-morpholinecarboxamidine-N-1-adamentyl-N-cyclohexyl hydrochloride (2·5 mg kg^?1, i.v.), significantly inhibited the femoral vasodilator response to intra-femoral arterial injection of cromakalim, an activator of K_ATP channels. In contrast, U37883A had no effect on the femoral vasodilator responses to nitroglycerin, isoprenaline, 5-HT, or 5-carboxamidotryptamine, suggesting this agent is a novel and selective inhibitor of hindlimb vasodilation induced by K_ATP-channel activation. Since U37883A did not significantly alter baseline femoral blood flow and femoral vascular resistance, the present data suggest that K_ATP channels do not contribute, in large measure, to regulating the canine femoral vascular bed under resting conditions in-vivo.