Ischemic preconditioning protects against infarction in rat heart.
We examined the anti-infarct effect of ischemic preconditioning in the rat heart. All hearts were subjected to 30 min of regional coronary ischemia and 2 h of reperfusion. Infarct size was determined by tetrazolium. The control group had an average infarct size of 31% of the risk zone. Three 5-min cycles of preconditioning ischemia limited the infarct size to 3.7%. Neither the adenosine receptor blocker PD 115,199 nor the ATP-sensitive potassium channel blocker, glibenclamide, could block this protection. Intracoronary adenosine A1-receptor agonist 2-chloro-N6-cyclopentyladenosine offered a significant anti-infarct protection to the isolated rat heart, however. Although one 5-min cycle of preconditioning did not protect the rat heart from infarction (31% infarction in risk zone), it did attenuate arrhythmias. We conclude that 1) the rat heart can be preconditioned, which argues against mitochondrial adenosinetriphosphatase being the mechanism of preconditioning; 2) the threshold for preconditioning is higher in rat than rabbit or dog; 3) a role for adenosine in preconditioning was only partially supported; and 4) a role for ATP-sensitive potassium channels was not supported.
Liu
Y
Y
Department of Physiology, University of South Alabama, Mobile 36688.
Downey
J M
JM
D000222:Adaptation, Physiological; D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D003327:Coronary Disease / Q000503:physiopathology*; D005905:Glyburide / Q000494:pharmacology; D006321:Heart / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D009203:Myocardial Infarction / Q000517:prevention & control*; D058914:Purinergic Antagonists; D051381:Rats; D017207:Rats, Sprague-Dawley; D017180:Tachycardia, Ventricular / Q000517:prevention & control; D014693:Ventricular Fibrillation / Q000517:prevention & control
D058914:Purinergic Antagonists; C058394:2-chloro-N(6)cyclopentyladenosine; D000241:Adenosine; D005905:Glyburide