Estimation of renal blood flow by use of endogenous N1-methylnicotinamide in rats.

The usefulness of the renal clearance of endogenous N1-methylnicotinamide (NMN) as a probe for estimating the renal blood flow (RBF) was examined in rats. And the effect of experimental acute renal failure (ERF) on RBF was also examined in rats treated with glycerol, folate, salicylate, uranium and gentamicin by using this method. No significant difference was shown between the values of RBF determined by the NMN method and conventional p-aminohippurate (PAH) method in both the intact (control) and glycerol-ERF rats, suggesting the usefulness of the NMN method in determining RBF. No significant difference was also shown in RBF between the control and all ERF-rats studied, through significant decreases in the renal clearance of NMN and renal extraction ratio (ER) were observed in the ERF-rats except the gentamicin-treated rats. It was suggested that the endogenous NMN would be a useful probe to estimate RBF without constant infusion of exogenous substances.