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Intracellular pH regulation in chicken enterocytes: the importance of extracellular pH
Author(s) -
Peral MJ,
Calonge ML,
Ilundain AA
Publication year - 1995
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1113/expphysiol.1995.sp003897
Subject(s) - extracellular , intracellular , enterocyte , intracellular ph , chemistry , microbiology and biotechnology , biophysics , biochemistry , biology , small intestine
The present work reports the effect of pHo on pHi and Na(+)‐H+ exchanger activity. Intracellular pH tended to follow pHo, but the proton distribution across the cell membrane is not at electrochemical equilibrium. Removal of external Na+ acidified the cells by both reversing the direction of the Na(+)‐H+ exchanger and hyperpolarizing the cell membrane potential. The relationship between pHo and the rate of Na(+)‐dependent proton efflux following an acid load suggests that external protons interact with the Na(+)‐H+ exchanger at a single site with an apparent pK (‐log of the dissociation constant) of 7.22. The results demonstrate that maintenance of pHo in the physiological range is essential for maintenance of normal cell pH and that the activity of the Na(+)‐H+ exchanger involved in pHi regulation is affected by external protons. The results also suggest that, at least at low pHo, some intracellular mechanism is involved in pHi regulation.