GLOMERULAR AND TUBULAR INTERACTIONS BETWEEN RENAL ADRENERGIC ACTIVITYAND NITRIC-OXIDE

Endothelium-dependent nitric oxide (EDNO) exerts control over the proc esses of glomerular filtration and tubular reabsorption. The importanc e of the renal nerves to the tonic influence of EDNO in the glomerular microcirculation and proximal tubule was tested by renal micropunctur e in euvolemic adult male Munich-Wistar rats. The physical determinant s of glomerular filtration and proximal reabsorption were assessed bef ore and during administration of the nitric oxide synthase inhibitor, N-G-monomethyl-L-arginine (L-NMMA), in control animals and in animals 5-9 days after either ipsilateral surgical renal denervation (DNX) or after either sham surgery (SHX). L-NMMA caused single-nephron glomerul ar filtration rate to decline in control and SHX animals but not in DN X rats. L-NMMA, caused a reduction in proximal reabsorption in control and SHX rats, which was prevented by prior DNX. DNX did not alter uri nary guanosine 3',5'-cyclic monophosphate excretion, and, although DNX upregulates glomerular angiotensin II (ANG II) receptors, prior DNX d id not alter intrarenal ANG II content as evaluated by radioimmunoassa y. Some component of renal adrenergic activity is required for the ful l expression of the glomerular and tubular effects of blockade of nitr ic oxide synthase.