Mode of nitric oxide action on the renal vasculature.

Our study aimed to characterize the essential cellular pathways along which nitric oxide (NO) exerts its well-known vasodilatatory properties in the kidney. Using the isolated perfused rat kidney model we examined the roles of potassium channels, cGMP-protein kinase activity and cAMP-phosphodiesterases (PDE) in the effect of NO on renovascular resistance. We found that neither potassium channel activity nor G-kinase activity was essential for the vasodilatatory effect of NO. The effect of NO, however, was essentially mimicked by pharmacological inhibition of PDE-3, which is a cGMP-inhibitable PDE. As PDE-3 is strongly expressed in renal preglomerular vessels and NO stimulates cGMP formation in renal vessels, it appears likely that inhibition of cAMP degradation and consequently the cAMP pathway are crucially involved in mediating the effects of NO on renal vascular resistance.