Sarcolemmal and mitochondrial K(ATP) channels and myocardial ischemic preconditioning

Ischemic preconditioning (IPC) is the phenomenon whereby brief periods of ischemia have been shown to protect the myocardium against a sustained ischemic insult. The result of IPC may be manifest as a marked reduction in infarct size, myocardial stunning, or incidence of arrhythmias. While many substances and pathways have been proposed to play a role in the signal transduction mediating the cardioprotective effect of IPC, overwhelming evidence indicates an intimate involvement of the ATP-sensitive potassium channel (K_ATP channel) in this process. Initial hypotheses suggested that the surface or sarcolemmal K_ATP (sarcK_ATP) channel mediated the cardioprotective effects of IPC. However, much research has subsequently supported a major role for the mitochondrial K_ATP channel (mitoK_ATP) as the one involved in IPC-mediated cardioprotection. This review presents evidence to support a role for the sarcK_ATP or the mitoK_ATP channel as either triggers and/or downstream mediators in the phenomenon of IPC.