[Intrinsic and endogenous mechanisms for protecting the heart against ischemia]

The heart has several possibilities to protect itself against ischemia. In general the protection measures are generated by the ischemia itself (intrinsic protection), but the protection can also be induced by external interventions not related to ischemia (endogenous protection). In this survey we have limited ourselves to cellular protection mechanisms. These mechanisms include: 1. The cessation of myocardial contraction immediately following the onset of ischemia; 2. myocardial hibernation, the phenomenon that in ischemic areas cardiomyocytes may dedifferntiate and switch to a fetal phenotype, probably to be better tolerant to hypoxia; 3. preconditioning, the enhanced tolerance against ischemia following short intermittent periods of ischemia and 4. the expression of protective proteins, like heat-shock or other stress proteins. The clinical importance of these protective mechanisms is briefly discussed.