The impairment of preconditioning-mediated cardioprotection in pathological conditions.

Myocardial ischemia is a condition in which the blood flow to the heart is diminished and thus the supply of oxygen and nutrients to the heart is reduced. The reperfusion to an ischemic myocardium often results in induction of infarction and cardiac dysfunction. The brief episodes of ischemia and reperfusion given before prolonged ischemia and reperfusion denotes ischemic preconditioning, which protects the heart from lethal ischemia-reperfusion injury. However, it is intriguing to note that the cardioprotective effect of preconditioning is suppressed in some pathological conditions such as hypercholesterolemia, hyperglycemia, hypertension, cardiac hypertrophy, aging, obesity and hyperhomocysteinemia. In this review, we have critically discussed the possible mechanisms involved in the modulation of cardioprotective potential of ischemic preconditioning in various pathological conditions.