Ischemic Preconditioning — A Pronounced and Endogenous Form of Protection against Tissue Injury

Abstract

Potentially one of the most important experimental findings in basic heart research over the past few years is the observation that short periods of myocardial ischemia can protect the heart against subsequent, more prolonged or severe periods of ischemia. This phenomenon, termed ‘ischemic preconditioning’, was highlighted in an important study by Murry, Jennings and Reimer working at Duke University in the United States and published in 1986 [1]. They showed that if dogs were subjected to brief (5 min) episodes of ischemia by complete coronary artery occlusion, each separated by brief periods of reperfusion or recovery, and were then subjected to a more prolonged (40 min) reocclusion of the same coronary artery, then infarcts in these hearts were much smaller, by up to 75%, than those in controls at any given level of coronary collateral flow. Preconditioning thus reduced the severity of the ultrastructural changes resulting from prolonged ischemia [1, 2]. Even a single brief period of ischemia can precondition the heart in this way [3].