title: Renal transport of NAP-taurine.
abstract: The renal transport of N-(4-azido-2-nitrophenyl)-2-aminoethylsulfonate (NAP-taurine), a potential photoaffinity label, was studied using the rabbit renal cortical slice and the isolated perfused rat kidney. NAP-taurine inhibited the slice accumulation of PAH in a dose-dependent manner (ID50 = 2.5 X 10(-5) M). It accumulated to a steady-state slice-to-medium concentration ratio of 14. However, NAP-taurine was not toxic to the tissue, as it did not influence the accumulation of the organic cation tetraethylammonium. NAP-taurine transport was saturable and its accumulation was inhibited by the metabolic inhibitors PAH, probenecid, 4,4'-diisothiocyano-2,2'-disulfonic stilbene (DIDS), ouabain, and the absence of sodium. Kinetic studies showed that the Km for NAP-taurine is 3.5 X 10(-5) M, and also that PAH competitively inhibits NAP-taurine influx with a Ki of 1.2 X 10(-3) M. Experiments with the rat isolated perfused kidney gave the NAP-taurine-to-inulin clearance ratio of approximately 5, indicating net tubular secretion. DIDS significantly reduced this clearance ratio to 0.8. The results suggest NAP-taurine is handled by the kidney in a manner analogous to PAH and may thus be useful as a photoaffinity label for the renal organic anion transport system.
mesh_terms: D000345:Affinity Labels / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D066298:In Vitro Techniques; D007668:Kidney / Q000187:drug effects / Q000502:physiology*; D007672:Kidney Cortex / Q000502:physiology*; D007700:Kinetics; D011188:Potassium / Q000378:metabolism; D011817:Rabbits; D051381:Rats; D012964:Sodium / Q000378:metabolism; D013654:Taurine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D010130:p-Aminohippuric Acid / Q000378:metabolism
chemical_list: D000345:Affinity Labels; D013654:Taurine; C010861:NAP taurine; D012964:Sodium; D011188:Potassium; D010130:p-Aminohippuric Acid