KATP channels mediate late preconditioning against infarction produced by monophosphoryl lipid A

TL;DRAbstract

The cardioprotective effect of myocardial preconditioning (PC) to reduce infarct size has been shown to last approximately 90 min (early PC), and then a second window of protection (SWOP or late PC) appears 24 h later. Although much work has been done to characterize early PC, little has been done to investigate potential mediators of SWOP. To that end, we have used monophosphoryl lipid A (MLA), a nontoxic endotoxin derivative, to produce SWOP and have examined the role of ATP-sensitive potassium (KATP) channels in mediating its cardioprotection. Adult mongrel dogs were given MLA (3, 10, or 35 micrograms/kg i.v.) 24 h before a 60-min left anterior descending coronary artery occlusion and 3 h of reperfusion. After reperfusion, the hearts were stained for myocardial infarction with triphenyltetrazolium. MLA produced a dose-dependent reduction in infarct size that was associated with an enhanced shortening of the monophasic action potential duration during early ischemia. To further exami

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