Renal dopamine not renal nerve mediates diuretic and natriuretic effect of ANF in rats.

Our previous study demonstrated that acutely or chronically unilateral renal denervation did not blunt intravenous ANF--induced hypotensive and ipsilateral renal effects. The present study was further to examine the permissive role of renal nerve and dopamine in the renal action of ANF. Experiments were conducted on anesthetized rats with either acute unilateral ureter ligation (n = 8), reserpine pretreatment (10 mg/kg, n = 7), mechanically controlled renal arterial pressure (n = 8) or blockade of dopamine D1 receptors by SCH23390 (n = 8, 0.8 micrograms/kg.min). The arterial blood pressure and renal clearance responses to intravenous (0.30-0.45 micrograms/kg.min) or intrarenal (0.10-0.15 micrograms/kg.min) infusion of ANF were measured. The results showed that unilateral ligation of the ureter to physiologically inhibit the contralateral renal efferent nerve activity did not alter the depressor, diuretic and natriuretic effects of ANF. Reserpine pretreatment blunted the diuretic and natriuretic response to intravenous administration of ANF. However, ANF-induced diuresis and natriuresis was persistently observed in both kidneys of rats with the left renal arterial pressure being controlled at a level comparable to that seen in the reserpine-pretreated group. Blockade of intrarenal dopamine D1 receptors by SCH23390 completely abolished the diuretic and natriuretic response to intrarenal infusion of ANF. These results support the notion that the diuretic and natriuretic effect of ANF is not resulted from a decrease in renal sympathetic efferent nerve activity, and further indicate that a mechanism associated with activation of the renal dopamine D1 receptors mediates the renal effect of ANF in rats.