Chloride dependency of renal brush-border membrane phosphate transport.
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.
Yanagawa
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Division of Nephrology, Sepulveda Veterans Affairs Medical Center, Los Angeles, California 91343, USA. nori@ucla.edu
Pham
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C
Shih
R N
RN
Miao
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S
Jo
O D
OD
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
D002712:Chlorides; D005561:Formates; D010710:Phosphates; C030544:formic acid