Phosphate transport by rat intestinal basolateral-membrane vesicles

F. K. Ghishan, K. Kikuchi, N. Arab

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

The characteristics of phosphate transport across intestinal basolateral membranes of the rat were determined by using enriched preparations in which uphill Na+-dependent D-glucose transport could not be demonstrated, but ATP-dependent Ca2+ transport was present. Phosphate transport was saturable, Na+-dependent and exhibited Michaelis-Menten kinetics. V(max.) was 51.1 ± 4.2 pmol/10 s per mg of protein and K(m) was 14 ± 3.9 μM. The transport process was electroneutral. Tracer-exchange experiments and counter-transport studies confirmed the presence of a Na+-P(i) carrier at the basolateral membrane. The presence of inside-positive membrane potential did not enhance phosphate uptake, indicating that the Na+ effect is secondary to the presence of the Na+-P(i) carrier rather than an induction of positive membrane potential. The stoichiometry of this carrier at pH 7.4 was 2 Na+:1 phosphate, as shown by direct studies utilizing the static-head method. These studies are the first to determine the presence of a phosphate carrier at the basolateral membrane.

Original languageEnglish (US)
Pages (from-to)641-646
Number of pages6
JournalBiochemical Journal
Volume243
Issue number3
DOIs
StatePublished - Jan 1 1987
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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