Opioid Receptors, KATP Channels and Ischemic Preconditioning

摘要: ATP-gated potassium channels (KATP) were initially identified in the myocardium by Noma1 using patch clamp methodology isolated guinea pig ventricular myocytes. Since its discovery, a number of factors and endogenous substances such as ATP/ADP ratio, certain nucleotide diphosphates, Mg++, lactate, pH, protein kinase C, adenosine bradykinin have been shown to modulate gating properties this channel heart.2 KATP activity is regulated metabolic state myocardial cell, originally proposed that would serve an cardioprotective function. Subsequently, it was opening produced ischemia resulted characteristic electrophysiological alterations including shortening action potential duration (APD) attenuation rate membrane depolarization. These changes be expected result decreased calcium influx via voltage-sensitive sodium-calcium exchange reduce overload lethal cell injury if timely reperfusion occur. A studies support hypothesis, although several recent reports suggest APD not essential mediating effect against infarction or stunning.3’4 Nevertheless, based upon numerous from laboratories species, there little doubt serves important role during ischemic hypoxic insults.