GABA-evoked depolarisations in the rat cortical wedge: involvement of GABAA receptors and HCO3- ions.
The effect of gamma-aminobutyric acid (GABA) was investigated on cortical wedges prepared from male Sprague-Dawley rats. GABA evoked concentration-dependent depolarisations (EC50: 0.8 mM), which were attenuated by up to 60% when bicarbonate-buffered aCSF was replaced with HEPES-buffered aCSF. Responses to 1 mM GABA were attenuated by (-)-bicuculline and picrotoxin and were potentiated by chlordiazepoxide and pentobarbitone. Ionotropic glutamate receptor antagonists had no effect. We conclude that GABA-evoked depolarisations are mediated via GABAA receptors, arising in part from HCO3- efflux from cells.
Phillips
I
I
CNS Biology, Knoll Pharmaceuticals Research & Development, Nottingham NG1 1GF, UK.
Martin
K F
KF
Thompson
K S
KS
Heal
D J
DJ
D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D001640:Bicuculline / Q000494:pharmacology; D002540:Cerebral Cortex / Q000187:drug effects* / Q000502:physiology*; D002707:Chlordiazepoxide / Q000494:pharmacology; D004594:Electrophysiology; D018756:GABA Antagonists / Q000494:pharmacology; D018757:GABA Modulators / Q000494:pharmacology; D066298:In Vitro Techniques; D007477:Ions; D010424:Pentobarbital / Q000494:pharmacology; D010852:Picrotoxin / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D001639:Bicarbonates; D001640:Bicuculline; D002707:Chlordiazepoxide; D018756:GABA Antagonists; D018757:GABA Modulators; D007477:Ions; D010424:Pentobarbital; D010852:Picrotoxin; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid