Abstract
Virgin and pregnant rats were studied to determine whether blood pressure and/or renal hemodynamics are influenced by the vascular actions of arginine vasopressin (AVP) via the V1 receptor. Blockade of the AVP-V1 receptor with receptor antagonist d(CH2)5VDAVP in anesthetized, volume-depleted rats produced similar falls in blood pressure in both virgin and late-pregnant rats even though the late-pregnant rats already exhibited gestational hypotension. In the conscious, normovolemic condition, AVP-V1 antagonism had no effect on blood pressure or renal hemodynamics in virgin or pregnant rats. These studies suggest that in nomal pregnancy the V1 vascular receptor of AVP does not maintain blood pressure or renal function. When the animal is stressed, AVP-V1 control of blood pressure is activated similarly in virgin and pregnant rats.