Nitric oxide seems to play a crucial role in sodium homeostasis and hence blood pressure regulation by controlling the tone of glomerular arterioles and mesanglum, medullary circulation, pressure natriuresis, tubuloglomerular feedback, renin release, and tubular function. Thus, deficiency of the L-arginine-nitric oxide pathway may be involved in the pathogenesis of such diseases as salt-sensitive hypertension, whereas activation of the nitric oxide system may either protect against or contribute to progression of various renal diseases.