Long-term effects of psychoemotional stress and tread-mill exercise on the microcirculatory system of rats

To answer the question of whether the increased intensity of tonic or of relaxing influences acting on the microcirculatory system predominate in various chronic psychoemotional stress situations and/or after long-lasting and intense tread-mill exercise, the left-ventricular wall of the heart and the skeletal muscle or pancreas of 49 experimental and 33 control animals were investigated, using a new histomorphometric method. Chronically stressed rats showed an increase of wall thickness in microvessels documenting a long-term increase of contractile performance of wall cells for the development and maintenance of an increased contractile tone; however, there were quantitative differences depending on the manner, intensity, and duration of stress. The opposite occurred in rats exercised by a tread-mill over 6 months, 3 h per day, demonstrating the morphological correlative of metabolic long-term autoregulation. An aversion stress applied simultaneously on these animals effectively antagonized the mentioned effects of exercise.