RESUMO
80 mongrel rats were studied for peculiarities of the heart activity regulation in dehydration, conditions of the vegetative homeostasis being different. Data of the variation pulsometry were used. A sympathetic shift of the vegetative homeostasis was a common dehydration-caused response. The shift was significant in rats with an initial equilibrium of the vegetative homeostasis and prevailing parasympathetic effects. The survival rate of this group of rats was high. In the group of rats with the initial prevalence of a sympathetic tonus a short-term sympathetic shift was replaced by an increase of parasympathetic effects. The survival rate of this group was much lower. Therefore, rats with initial prevalence of the sympathetic compartment tonus of the vegetative nervous system are more labile to the effect of the dehydration stress.