Plasma vasopressin concentration in high sodium renal hypertension

One-kidney, figure-8 renal wrapped and sham-operated rats maintained on high sodium intake were studied to determine plasma concentrations of vasopressin during the onset of hypertension. Animals were chronically prepared with femoral artery and vein catheters. Arterial blood samples were taken from conscious rats before and 3 days after renal wrap or sham operation while donor blood was simultaneously infused intravenously. Three days after surgery, arterial pressure, plasma osmolality and plasma vasopressin concentration increased significantly in the renal wrapped animals and remained unchanged in the sham-operated rats. Ganglionic blockade with hexamethonium and atropine produced equivalent decreases in arterial pressure and increases in plasma vasopressin concentration in the two groups of rats. Subsequent administration of the V1 vasopressin antagonist, d(CH2)5Tyr(Me)AVP, caused a significantly greater fall in arterial pressure in the hypertensive rats. These results provide further evidence for a contribution of vasopressin to sodium-dependent hypertension.