Reaction of rat brain capillaries to immobilization stress.

The calcium adenosine triphosphate method of Chilingaryan was used to study the morphofunctional state of the capillary component of the microcirculatory bed of the brain in rats at different time points after experimental immobilization stress (fixation of the animal on its back for 2 h). Analysis of morphometric data showed that in comparison with intact animals, stress was immediately followed by constriction of capillaries by 17.2%, with compensatory dilation by 2.5% occurring at two days, and subsequent minor constriction by 5.6%. Morphometric measures in placid and aggressive animals showed that the behavioral stereotype of placid animals produced a more sparing physiological response to stress. It is suggested that the difference in capillary dysfunction is largely dependent on impairment of neuronal systems involved in regulating the microcirculation.