[State of the endothelium of the aorta during chronic stress].

In 50 white male rats (18-control and 32-experimental) using morphometrical and stereological methods for film preparations of endothelium, the state of the internal aortal lining at various stages of chronic stress developing during muscular activity has been studied. The data obtained are statistically treated by the sliding averages method, reliability of the differences is estimated according to the value of nonparametrical criterion of Wilcoxon-Mann-Whitney. For objective periodization of the endothelial reaction to stress, centered moving averages curves are performed with subsequent calculation of the coefficient of variation for the aligned ordinates of the approximated values in every temporal point. The aortal endothelium reaction to the stress is of phasic character. During the alarm reaction, destructive changes predominate; they are accompanied with an increased mitotic activity of endotheliocytes up to 2.2%. The resistance stage increases compensatory-adaptive rearrangements, which are manifested not only as cellular hyperplasia, but as hyperthrophy of nuclei, increasing number of strangulated nuclei, nucleoli, as well as binuclear and trinucler cells. To the exhaustion period the increase of alternative and restorative transformations of the tissue corresponds.