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Electrogenic Na + /HCO 3 − cotransport in neuroglia
Author(s) -
Astion Michael L.,
Orkand Richard K.
Publication year - 1988
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/glia.440010508
Subject(s) - cotransporter , depolarization , necturus , biophysics , neuroglia , membrane potential , conductance , sodium , chemistry , biology , membrane , endocrinology , medicine , biochemistry , central nervous system , physics , organic chemistry , condensed matter physics
Membrane potential recording from glial cells in Necturus optic nerve in the presence of 2 mM Ba ++ , which was added to block the K + conductance, gave the following results. (1) In HCO 3 − ‐free, low‐Na + solutions (11% of control; Na + replaced with N‐methyl‐D‐glucamine), the hyperpolarizing effect of adding 10 mM HCO 3 − was reduced by approximately 80%.(2) 4‐acetamido‐4′‐isothiocynato‐stilbene‐2,2′‐disulfonic acid (SITS, 0.1 or 1 mM) reduced the effect of HCO 3 − by at least 50%.(3) In the presence of HCO 3 − , reduction of Na + caused a depolarization which was much larger than that observed in nominally HCO 3 − ‐free solutions. These observations indicate the presence in the glial membrane of an electrogenic Na + /HCO 3 − contransporter in which the stoichiometry of HCO 3 − to Na + is greater than 1.