Phenomenon of the adaptive stabilization of sarcoplasmic and nuclear structures in myocardium.

In adaptation of rats to repeated stress exposure, a mechanism gradually forms at the level of heart to provide a considerable increase in the organ resistance to reperfusion paradox and toxic concentrations of catecholamines and Ca2+. Sarcoplasmic reticulum and mitochondria isolated from the hearts of adapted animals are highly resistant to autolysis, and nuclei to the damaging action of one-chain DNA. These changes are named phenomenon of the adaptive stabilization of structures (PhASS). An important role of myocardial heat shock protein (HSP) accumulation in the mechanism of PhASS is shown. The development of PhASS is accompanied by an increased resistance of myocardium to ischemic necrosis.