Nitric oxide increases renal blood flow by interacting with the sympathetic nervous system

To investigate whether changes in renal blood flow induced by nondepressor doses of L-arginine, the precursor of nitric oxide, are mediated by a sympathetic neural mechanism, we examined the following in conscious rabbits: (1) the effects of intravenous infusion of L- or D-arginine (15 to 200 mumol/kg per minute) on renal blood flow and renal sympathetic nerve activity with or without intravenous infusion of a nonpressor dose of NG-monomethyl-L-arginine (L-NMMA), a nitric oxide synthase inhibitor, and (2) the effects of L-arginine on renal blood flow after renal denervation with or without L-NMMA pretreatment. In renal innervated rabbits, L-arginine (100 and 200 mumol/kg per minute) increased renal blood flow by 9 +/- 2 and 16 +/- 3 mL/min (P < .05, respectively) and decreased renal sympathetic nerve activity by 12 +/- 4% and 19 +/- 3% of control (P < .05, respectively). In contrast, no changes occurred in any variable during D-arginine infusion. L-NMMA attenuated the renal blood flow and renal sympathetic nerve activity responses to L-arginine (P < .05). In renal denervated rabbits, L-NMMA also attenuated the renal blood flow responses to L-arginine (P < .05) and abolished them (P < .05) compared with those in renal innervated rabbits. All renal blood flow responses to L-arginine were accompanied by parallel changes in plasma L-citrulline concentration.(ABSTRACT TRUNCATED AT 250 WORDS)