Regional ischemic 'preconditioning' protects remote virgin myocardium from subsequent sustained coronary occlusion.

BACKGROUNDOne or more brief episodes of coronary artery occlusion protect or precondition the myocardium perfused by that artery from a subsequent episode of sustained ischemia. We sought to determine whether ischemic preconditioning protects only those myocytes subjected to brief coronary occlusion or whether brief occlusions in one vascular bed also limit infarct size and/or attenuate contractile dysfunction in remote virgin myocardium subjected to subsequent sustained coronary occlusion.METHODS AND RESULTSIn the preliminary limb of the study, six anesthetized dogs underwent four episodes of 5-minute circumflex branch occlusion plus 5-minute reperfusion, followed by 1 hour of sustained left anterior descending coronary artery occlusion and 4.5 hours of reflow. Subendocardial blood flow during left anterior descending coronary artery occlusion (measured by injection of radiolabeled microspheres) was 0.07 +/- 0.03 mL.min-1 x g tissue-1, similar to the value of 0.07 +/- 0.02 mL.min-1 x g-1 observed in a ...