title: Chloride dependency of renal brush-border membrane phosphate transport.
abstract: In our present study, we examined the effect of Cl(-) on rabbit renal brush-border membrane (BBM) phosphate (P(i)) uptake. It was found that the Na(+)-dependent BBM (32)P uptake was significantly inhibited by Cl(-) replacement in the uptake solution with other anions, or by Cl(-) transport inhibitors, including DIDS, SITS, diphenylamine-2-carboxylate (DPC), niflumic acid (NF), and 5-nitro-2-(3-phenylpropylamino)benzoate (NPPB). Intravesicular formate or Cl(-) increased BBM (36)Cl(-) uptake but did not affect BBM (32)P uptake. BBM (22)Na(+) uptake was lowered by Cl(-) replacement in the uptake solution but not by Cl(-) transport inhibitors. Changes in transmembrane electrical potential altered BBM (36)Cl(-) and (32)P uptake in directions consistent with a net inward movement of negative and positive charges, respectively. However, the Cl(-)-dependent BBM P(i) uptake was not affected by changes in transmembrane electrical potential. Finally, a similar Cl(-) dependency of P(i) uptake was also found with BBM derived from rat and mouse kidneys. In summary, our study showed that a component of Na(+)-dependent P(i) uptake was also Cl(-) dependent in rabbit, rat, and mouse renal BBM. The mechanism underlying this Cl(-) dependency remains to be identified.
authors.affiliation: Division of Nephrology, Sepulveda Veterans Affairs Medical Center, Los Angeles, California 91343, USA. nori@ucla.edu
authors.forename: N
authors.initials: N
authors.lastname: Yanagawa
authors.forename: C
authors.initials: C
authors.lastname: Pham
authors.forename: R N
authors.initials: RN
authors.lastname: Shih
authors.forename: S
authors.initials: S
authors.lastname: Miao
authors.forename: O D
authors.initials: OD
authors.lastname: Jo
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000502:physiology; D002712:Chlorides / Q000037:antagonists & inhibitors / Q000502:physiology*; D004594:Electrophysiology; D005561:Formates / Q000378:metabolism; D007668:Kidney / Q000378:metabolism* / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008871:Microvilli / Q000378:metabolism / Q000502:physiology; D010710:Phosphates / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D002712:Chlorides; D005561:Formates; D010710:Phosphates; C030544:formic acid