Coupled sodium-chloride transport by rabbit ileal brush-border membrane vesicles

C. C. Fan, R. G. Faust, D. W. Powell

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Abstract

Uptake of Na and Cl into brush-border membrane vesicles isolated from rabbit ileal epithelial cells was investigated with a rapid filtration technique using 22Na and 36Cl as tracers. The rank order of anion dependence for Na uptake in the absence of anion gradients was Cl ≃ SNC > NO3 > gluconate. The sequence of cation specificity for Cl uptake was Na ≃ Li > K > choline. The transport of Na and Cl were both inhibited by harmaline, furosemide, 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid, and 4,4'-diisothiocyano-2,2'-stilbene disulfonic acid. Carrier mediation of Cl-stimulated Na transport was suggested by the competition for 22Na uptake with increasing concentrations of unlabeled Na in the presence of Cl but not when gluconate was the counterion. Chloride-dependent Na uptake had an apparent K(m) of 4.5 mM and a V(max) of 20 mmol.mg prot-1.15 s-1. Na-H exchange and Cl-OH (or HCO3) exchange were also demonstrated in these vesicles. These findings confirm the presence of an electrically neutral carrier-mediated, Na-Cl-coupled transport process in the apical cell membrane of rabbit ileal epithelial cells. The nature of the coupling of Na to Cl transport, i.e., NaCl symport or a process that combines Na-H antiport with Cl-OH (or HCO3) antiport, remains to be determined.

Original languageEnglish (US)
Pages (from-to)G375-G385
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume7
Issue number4
StatePublished - Jan 1 1983

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ASJC Scopus subject areas

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

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