[Structural reorganization of the myocardium during exposure to extreme environmental conditions]

The left ventricular myocardium of Wistar rats was studied by stereologic methods under the exposure to low temperature (-7 degrees C), after a single overheating (at 43 degrees C), during adaptation to high altitudes (3200 above the sea level) and after transferring to high latitudes (at 69 of the North). It was shown that tissue spatial reorganization of the myocardium proceeded by stages: at the first stage the volume and surface-to-volume ratios of bulk tissue components (especially cardiomyocytes and capillaries) were changed considerably, at the second stage the tendency to normalization of tissue architectonics was observed. This dynamics of tissue reorganization is likely to be conditioned by stress reaction and reveals some structural mechanisms of non-specific response to extreme impact. On the contrary, an ultrastructural spatial reorganization of cardiomyocytes was characterized by continuous disproportional changes of volume ratios of bulk organelles (especially mitochondria and myofibrils), which were evident during influence of environmental factors. These discrepancies in dynamics of tissue and intercellular spatial reorganization of myocardium are supposed to reflect the fundamental peculiarities of spatial-temporal organization of regenerative processes in parenchymal cells and stromal components.