The Role of ATP-Sensitive Potassium Channels in Myocardial Ischemic Stress

Publisher Summary This chapter focuses on the pharmacological effects of the adenosine triphosphate (ATP)-sensitive class of potassium channel blockers and openers on the function of the ischemic-reperfused myocardium. The importance of ATP-sensitive potassium channel (K+ATP) blockers and openers is recognized in the regulation of stress-induced, functional changes in the myocardium (example, by ischemia, reperfusion, and preconditioning) and this recognition is having a major impact on the regulation of cardiac function in ischemic-reperfused hearts. The use of (K+ATP) blockers or openers is not always beneficial and may have some detrimental effects, especially in the ischemic-reperfused myocardium. The chapter also discusses (K+ATP) channel openers. The properties of KATPchannels vary according to the type of tissue, and at least three major classes are currently recognized: (1) the type I channels, blocked by micromolar concentrations of intracellular ATP, are present in cardiac, skeletal, smooth muscle, and pancreatic β cells. The pancreatic β cell is the more sensitive to ATP, and these cells are sensitive to voltage and calcium ions. (2) The type II channel, originally described in neurons is inhibited by millimolar concentrations of ATP. (3) The type III channel, found in tracheal smooth muscle and some epithelial cells, is similar to the type II in its sensitivity to ATP, but differs in being activated by micromolar concentrations of calcium.