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Phosphate efflux from jejunal enterocytes of the rat: Effect of phosphate concentration gradient and pH
Author(s) -
AlSawan S.,
Skillen A. W.
Publication year - 1992
Publication title -
cell biochemistry and function
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.933
H-Index - 61
eISSN - 1099-0844
pISSN - 0263-6484
DOI - 10.1002/cbf.290100408
Subject(s) - efflux , phosphate , extracellular , pi , intracellular , chemistry , brush border , epithelial polarity , membrane , biophysics , enterocyte , michaelis–menten kinetics , intracellular ph , flux (metallurgy) , biochemistry , small intestine , biology , enzyme , enzyme assay , vesicle , organic chemistry
The effect of variation in the intracellular and extracellular phosphate concentration on the Pi efflux across the basolateral membrane of pre‐loaded enterocytes has been examined. Efflux rate constants for Pi fell from 0·89 h −1 to 0·68 h −1 as the extracellular Pi concentration was increased from 0·5 m M to 5 m M . As the intracellular Pi concentration was raised from 0·5 to 3 m M the rate constant dropped from 0·95 h −1 to 0·77 h −1 . The findings are indicative of the presence of Pi‐specific transporter at the basolateral membrane. The efflux rate constant of Pi at pH 7·1 was higher than that at pH 7·4 suggesting that the Pi flux across the basolateral membrane of enterocytes follows a similar pattern towards pH changes as do fluxes across the brush‐border membrane.