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Differences in reversed plasmalemmal Na/Ca exchange activities among neuronal subtypes
Author(s) -
Kiedrowski L.
Publication year - 2003
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.85.s2.18_9.x
Subject(s) - excitotoxicity , chemistry , efflux , neuroscience , microbiology and biotechnology , biophysics , biochemistry , biology , glutamate receptor , receptor
Under pathological conditions, when the Na + and K + concentration gradients collapse, plasmalemmal K‐dependent (NCKX) and K‐independent Na/Ca exchangers (NCX) may reverse and contribute to toxic Ca 2+ accumulation. Vulnerability to ischemia or excitotoxicity greatly varies among neuronal subtypes and may be related, in part, to differences in reverse NCKX and/or NCX activities. Cultured cerebellar granule cells (CGCs) are more resistant to excitotoxicity than forebrain neurons (FNs). To examine whether NCKX or NCX activities in CGCs differ from those in FNs, cytosolic [Ca 2+ ] transients mediated by reversed NCX and NCKX were monitored. NCKX and NCX reversal was triggered by gramicidin‐induced Na + influx and K + efflux. The NCX reversal was inhibited by 10 μ m KB‐R7943, and that of NCKX by removal of external K + . In FNs, reversed NCX activity was much more robust than in CGCs, however, activity of reversed NCKX was similar. These data support the idea that vulnerability to excitotoxicity may be linked to reversal of plasmalemmal Na/Ca exchangers. Acknowledgement: Supported by NS37390.