RESUMO
BACKGROUND: The regulation of renal hemodynamics is closely related to the L-arginine (L-Arg)/nitric oxide (NO) pathway. NO - metabolized from L-Arg - is capable of improving renal function in ischemic and toxic acute renal failure (ARF), while NO synthase (NOS) inhibition induces deterioration in renal function. The mortality rate in patients with septic shock is increased when treated with a non-selective NOS inhibitor, while the incidence of ARF requiring renal replacement therapy is unaffected. To date, there are no studies on the impact of NOS substrate (L-Arg) and inhibitor (L-NMMA) on renal function in early lipopolysaccharide (LPS)-induced ARF. METHODS: ARF was induced by intravenous (i.v.) LPS. Animals were treated with L-Arg, L-NMMA (NOS substrate and inhibitor), a combination of both or saline. Glomerular filtration rate (GFR), urine flow, fractional sodium excretion, excretion of NO metabolism stable end products and blood pressure (BP) were recorded at baseline, after ARF induction, during drug infusion and thereafter. RESULTS: L-Arg induced better GFR during infusion. Excretion of the NO metabolism end products was highest in the L-Arg group and lowest in the NOS inhibitor group. L-Arg administration had no influence on BP, while L-NMMA induced a slight elevation. CONCLUSIONS: We conclude that exogenous L-Arg exerts beneficial effects in early LPS-induced ARF in rats during drug infusion, while NOS inhibition has no influence on GFR. Subcellular compartmentalization of the L-Arg pool in cytoplasma and the rapid utilization of exogenous L-Arg in such a micro-environment could explain this effect, which has been observed in other ARF models and was called the "L-Arg paradox". In further studies the effects of early and prolonged administration of L-Arg in endotoxinemia should be investigated.
