[The structural reorganization of the myocardium in white rats under exposure to high temperature]

The investigation was performed in 64 male albino rats, 18 of which stayed in comfortable conditions (control), while 48 were kept everyday for 4 hrs in open sun ground at temperature 30-40 degrees C during 3 months. Vascular-structural reorganizations in the myocardium of experimental animals developed during 1-15 days. Capillary-tissue disturbances increase with characteristic morphological manifestations of the blood circulation disorders prevailing in the left and right ventricles, sharp increase of vessel and capillary wall permeability, loosening of the organ stroma, dystrophic and degenerative processes in cardiomyocytes, presence of diapedese haemorrhages and decrease of glycogen content. From day 16 up to day 30 capillary-tissue disorders and manifestations of the structural-anatomic reorganizations subside although intramural blood circulation changes persist as well as single degenerative changes in cardiomyocytes and oedematous changes of the connective tissue framework. At later stages, up to day 90 the formed structural anatomical reorganizations stabolize, the signs of blood circulation disturbances disappear to significant extent, but complete normalization of microscopic myocardial structure does not occur.