Abstract
Renal glomeruli isolated from Wistar rats were incubated with substances that modify nitric oxide (NO) synthesis in the presence of the phosphodiesterase inhibitor IBMX and glomerular cGMP production was measured by radioimmunoassay. Glomeruli incubated in basal conditions produced 0.15 ± 0.02 pmol cGMP/mg protein. Acetylcholine (0.1 μM) and bradykinin (0.1 μM) increased cGMP production by 113% and 183%, respectively. N-nitro-L-arginine-methyl ester (L-NAME) (0.1 mM), a NO synthetase inhibitor, completely blocked the increase induced by acetylcholine or bradykinin. L-NAME or methylene blue (1 μM) alone had no significant effect on basal cGMP production. L-arginine (1 μM) increased glomerular cGMP production approximately fourfold. Maximal cGMP stimulation (about sixfold) was obtained with ANP 0.1 μM. Endothelin also increased cGMP production (65%), this action being blocked by L-NAME. These data suggest that NO can be synthesized in glomerulus and that NO stimulates soluble guanylate cyclase to modulate glomerular function.