[Action of vasopressin on the electrical and contractile reactions of vascular smooth muscles in animals of various ages].

Vasopressin action on isolated strips of the femoral artery was studied in mature and old rats. Vasopressin has been shown to depolarize smooth muscle cells (SMC) membranes, causing the tonic contraction of the strips. SMC sensitivity to vasopressin in old animals was increased, electrical and contractile reactions were also enhanced. Peculiar tachyphylaxia in response to vasopressin has been found in SMC of mature animals. In old animals SMC tachyphylaxia was far less expressed than in mature ones. Two types of vasopressin receptors (V1-exciting and V2-inhibitory) in vascular SMC were suggested. Vasopressin does not influence cAMP content of the femoral artery in mature and old animals. Specific features of SMC reactions to vasopressin in old animals may underlie the mechanisms of cardiovascular pathology in old age.