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Voltage‐dependent Na + ‐HCO 3 − cotransporter and Na + /H + exchanger are involved in intracellular pH regulation of cultured mature rat cerebellar oligodendrocytes
Author(s) -
Boussouf Abdelhamid,
Lambert Regis C.,
Gaillard Stephane
Publication year - 1997
Publication title -
glia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.954
H-Index - 164
eISSN - 1098-1136
pISSN - 0894-1491
DOI - 10.1002/(sici)1098-1136(199701)19:1<74::aid-glia8>3.0.co;2-a
Subject(s) - cotransporter , biology , intracellular ph , intracellular , cerebellum , neuroscience , microbiology and biotechnology , sodium , chemistry , organic chemistry
Intracellular pH (pH i ) was measured at 37°C in mature rat cerebellar oligodendrocytes dissociated in culture by using the pH‐sensitive probe BCECF. Cells were identified by anti‐galactocerebroside antibody. The mean steady‐state pH i was 7.02 in the absence of CO 2 /bicarbonate (Hepes‐buffered solution) at an external pH of 7.40 and 7.04 in 5% CO 2 /25 mM bicarbonate‐buffered solution at the same external pH; this value was modified neither by the removal of external chloride nor by the addition of the chloride‐coupled transport blocker DIDS. In both external solutions steady‐state pH i values were strongly dependent on external pH. In Hepes‐buffered solution pH i recovery following an acid load required external Na + and was completely inhibited by amiloride, indicating the presence of a Na + /H + exchanger. In CO 2 /bicarbonate‐buffered solution amiloride partially reduced the pHi recovery rate, indicating the presence of a bicarbonate‐dependent pH i regulating mechanism. Membrane depolarization induced by increasing external K + concentration elicited an alkalinization only in the presence of external Na + and bicarbonate. Analysis of the calculated HCO 3 fluxes with respect to membrane potential indicated that these fluxes were mediated by a Na + ‐HCO 3 cotransport with a stoichiometry of 1:3. These results demonstrate that a Na + /H + exchanger and a Na + HCO 3 cotransporter are involved in pH i regulation of mature oligodendrocytes. GLIA 19:74–84, 1997. © 1997 Wiley‐Liss, Inc.