ATP-sensitive K+ channels of the cardiovascular system

Abstract

ATP-sensitive K+ (KATP) channels are inhibited by intracellular ATP and activated by intracellular nucleoside diphosphates, and thus provide a link between cellular metabolism and excitability. They are widely distributed in various tissues including heart and vasculature, and thus may play essential regulatory roles in the cardiovascular system. Furthermore, KATP channels are the targets of two important classes of drugs, i.e., the antidiabetic sulfonylureas which block the channels, and a series of vasorelaxants called "K+ channel openers" which tend to maintain the channels in an open conformation. Recently, the molecular structure of KATP channels has been clarified in various tissues including cardiovascular system to be a complex of at least two subunits, i.e. SUR and Kir6.0. The KATP channels in heart and vascular smooth muscle now appear to be the complexes of SUR2A/Kir6.2 and SUR2B/Kir6.1, respectively. Further works are now in progress to understand the molecular mechanisms responsible for the control of KATP channel function by intracellular nucleotides and drugs.