Coupling between reduced nicotinamide adenine dinucleotide oxidation and metabolite transport in renal brush border...

In a previous communication [Giménez-Gallego, G., Benavides, J., García, M.L., & Valdivieso, F. (1980) Biochemistry (preceding paper in this issue)] we have reported the occurrence of a NADH oxidase activity in the renal brush border membranes. The brush border membranes can utilize the energy from the oxidation of NADH to drive the transport of amino acids (aspartic and glutamic acids), organic acids, and the lipophilic cation tetraphenylphosphonium (TPP). The coupling between NADH oxidation seems to be due to the formation of a proton electrochemical gradient (delta-mu H+) as indicated by the effect of specific ionophores. This system may be implicated in the reabsorption process in the renal tubules and in the maintenance of the delta-mu H+ (positive and acidic in the luminal side) previously described in the renal tubules "in vivo".