Ethanol-induced Cl- flux in rat cerebellar granule cells as measured by a fluorescent probe.
Cl- fluxes through the GABAA receptor gated ion channels in cultured rat cerebellar granule cells were measured using the chloride-sensitive fluorescent probe SPQ (6-methoxy-N-(3-sulphopropyl)quinolinium) incorporated into the cells. The fluorescence of SPQ is quenched by Cl- ions. The cells were bathed in a low Cl- medium so that the Cl- gradient was directed outward. Ethanol increased the SPQ fluorescence indicating a decrease in intracellular Cl- due to Cl- efflux. Picrotoxin inhibited the effect at low concentrations of ethanol (less than 50 mM) in a concentration dependent manner. The effects of ethanol were potentiated at low concentrations (less than 10 microM) of gamma-aminobutyric acid (GABA), but inhibited at higher concentrations (0.3-2.0 mM). The results support the hypothesis that ethanol may act via the GABAA receptor gated ion channel. The results also suggest that SPQ is a suitable probe for measuring GABAA receptor-coupled Cl- fluxes through the GABAA receptor-gated channels in living cells.
Engblom
A C
AC
Department of Biochemistry and Pharmacy, Abo Akademi, Finland.
Holopainen
I
I
Akerman
K E
KE
D000818:Animals; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000494:pharmacology*; D005665:Furosemide / Q000494:pharmacology; D015640:Ion Channel Gating / Q000187:drug effects; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D051381:Rats; D011919:Rats, Inbred Strains; D011963:Receptors, GABA-A / Q000187:drug effects / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D002712:Chlorides; D007473:Ion Channels; D011963:Receptors, GABA-A; D000431:Ethanol; D005680:gamma-Aminobutyric Acid; D005665:Furosemide