sentence: β - cell and cardiac K channels comprise Kir6.2 / SUR1 and Kir6.2 / SUR2A respectively , and it is likely that the dominant channel in most vascular smooth muscle comprises Kir6.1 / SUR2B.98 99 In our own experiments , we demonstrated the presence of single channel activity , which was inhibited by both intracellular ATP and by the sulphonylurea compound glibenclamide .