NITRIC-OXIDE AND THE IMMATURE KIDNEY

Nitric oxide (NO) is a very potent vasodilator synthesized from L-argi nine by endothelial cells. By activating guanylate cyclase, it promote s vasodilatation of adjacent smooth muscle cells. NO is thus involved in the control of vascular tone in various organs. There is increasing evidence that NO is tonically synthesized within the kidney and plays a crucial role in the modulation of renal hemodynamics and excretory function. The blockade of basal NO synthesis has been shown to result in decreases in renal blood flow and, to a lesser extent, in glomerula r filtration rate. NO may also be involved in sodium excretion. In the neonatal period, a time associated with a hyperactivation of vasoacti ve systems, NO seems to play a greater role than in the adult. It coul d also be implicated in the response to vasoconstrictive stresses, suc h as perinatal hypoxia, frequently encountered during this period.