[Effect of restricted oxygenation of vascular smooth muscles on the contractile effects of direct electrical and mechanical stimulation].

Contractility reactions of the smooth muscles of the rat portal vein and the umbilical vein of man to direct electrical stimulation and rapid stretch were examined under different PO2 levels in perfusate. It was shown that during perfusion of vascular preparations with oxygenated Krebs solution, the active myogenic responses to rapid stretch and contractility reactions to electrical stimulation are well pronounced and dependent on the stimulation intensity. The decrease in perfusate PO2 is accompanied by a considerably less increment of the amplitude of spontaneous contractions and tonic tension of the smooth muscles in response to direct mechanical and electrical stimulation, respectively. The data obtained allow a suggestion that physiological variation of the PO2 level may influence the reactivity and myogenic activity of the vascular smooth muscles and that this mechanism may participate in the local blood flow control and correction of central neurogenic effects.