Compensatory pressor role of vasopressin following acute diuresis

Recent interest has focused on the role of vasopressin (AVP) in blood pressure (BP) regulation. This study was performed to determine if vasopressin has a compensatory pressor role following acute diuresis in both normal rats and in rats with subtotal nephrectomy (SN) or in rats with SN-salt induced hypertension. An inhibitor (AVP-I), specific for the AVP vascular smooth muscle receptor, was administered intravenously to assess the AVP dependency of the BP. Furosemide administration significantly increased plasma AVP levels in all rats. Administration of AVP-I did not change BP in the normal rats with or without prior furosemide administration or in the SN rats without furosemide administration. In contrast, after furosemide administration, AVP-I significantly decreased mean BP in the SN rats. The administration of AVP-I to the SN-salt hypertensive rats, with or without furosemide administration, significantly decreased mean BP. In conclusion, AVP has a compensatory pressor role in SN rats after acute diuresis, with or without salt-induced hypertension, but not in the normal rat.