[Subcellular reorganization of cardiomyocytes during and after temporary experimental hypothermic circulatory arrest]

Ultrastructure of cardiomyocytes of the left ventricle has been studied in dogs during the experiments, performed with a general external cooling, prolonged circulatory arrest, as well as during long term periods after the operation. In the experiment without cooling it is not possible to restore hemodynamics after 30 min of total ischemia. In cardiomyocytes severe, sometimes irreversible lytic lesions are registered. Opposite to this, by the end of one hour's cardiac arrest under total cooling up to 24-22 degrees C, changes in ultrastructure of cardiomyocytes are minimal. This is proved by a stabilizing action of hypothermia to membranous, fibrillar and even labile granular cellular components. More manifested changes occur in cells after restoration of the cardiac activity and worming, though even at this stage certain morphological signs of partial restoration of synthetic processes are noted. By the third day after the operation ultrastructure of cardiomyocytes is fully normalized at an essential hypertrophy and hyperplasia of protein synthesis organels and lysosomes. Thus, under conditions of aperfusional hypothermia (24-22 degrees C) and cardiac arrest, produced with pharmacological cooling, cardiomyocytes safely survive one hour's total ischemia, presenting their ability to intracellular regeneration in full.