Differences in the mechanism of metabolic regulation of ATP-sensitive K+ channels containing Kir6.1 and Kir6.2 subunits.

Abstract

ATP sensitive K(+) channels (K(ATP)) sense adenine nucleotide concentrations and thus couple the metabolic state of the cell to membrane potential. The hetero-octameric complex of a sulphonylurea receptor (SUR2B) and an inwardly rectifying K(+) channel (Kir6.1) and the corresponding native channel in smooth muscle are relatively insensitive to variations in intracellular ATP. Activation of these channels in blood vessels during hypoxia/ischaemia is thought to be mediated via hormonal regulation such as cellular adenosine release or the release of mediators from the endothelium. In contrast, intracellular ATP prominently inhibits Kir6.2 containing complexes, such as those present in cardiac myocytes. Thus, we investigated differences in the mechanism of metabolic regulation of Kir6.1 and Kir6.2 containing K(ATP) channels.