NITRIC-OXIDE IN HYPERTENSION AND RENAL DISEASES

Nitric oxide (NO) is intimately involved in the regulation of vascular tone, renal haemodynamics and sodium balance. The physiological actio ns of NO suggest important vascular and renal protective roles for NO. When produced in large amounts, however, NO may also mediate cytotoxi c effects. Increasing evidence suggests that endothelial function, not ably the NO pathway may be compromised in hypertension. It is not know n, however, whether changes in endothelial function are primary or sec ondary to the development of hypertension. In renal diseases evidence for both excessive and deficient activity of NO pathway has been found . Increased glomerular production of NO via inducible NO synthase (NOS ) with potential cytotoxic consequences has been demonstrated in exper imental acute glomerulonephritis. On the other hand, indirect evidence obtained by means of NOS inhibitors point out to an important renopro tective role for NO in renal diseases. NO may counteract disease progr ession in renal diseases by preventing glomerular microthrombi, mainta ining renal perfusion and medullary oxygenation, and via its anti-infl ammatory/antiproliferative effects. However, these beneficial effects of NO may be compromised (endothelial and/or tubular dysfunction) in c hronic nephropathies resulting in an accelerated course of renal disea se. In future, more specific inhibitors and activators of different NO S isoforms are needed to elucidate the role of NO in various renal dis eases in detail, and for treatment strategies aimed at modifying the N O pathway.