Differing actions of baclofen and 3-amino-propylphosphinic acid in rat neocortical slices.
Rat neocortical slices maintained in Mg2(+)-free Krebs medium developed spontaneous paroxysmal discharges which were attenuated or suppressed by the gamma-aminobutyric acid-B (GABAB) receptor agonist baclofen, occasionally accompanied by a slight hyperpolarisation, and antagonised by the specific GABAB-receptor antagonist, 2-OH-saclofen. Over the same dose range, the GABA-analogue 3-amino-propylphosphinic acid (3-APA) caused a marked, prompt hyperpolarisation with little or no effect on the frequency of the discharges, although their amplitude was attenuated. In the presence of 2-OH-saclofen, 3-APA still induced a hyperpolarisation but the amplitude of the discharges was no longer affected. This marked difference in action between baclofen and 3-APA in the rat neocortical slices suggests there may be a heterogeneity of GABAB-receptors.
Ong
J
J
Department of Anaesthesia and Intensive Care, University of Adelaide, Australia.
Kerr
D I
DI
Johnston
G A
GA
Hall
R G
RG
D000818:Animals; D001418:Baclofen / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000187:drug effects / Q000502:physiology*; D005071:Evoked Potentials / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D005680:gamma-Aminobutyric Acid / Q000031:analogs & derivatives / Q000502:physiology*
D005680:gamma-Aminobutyric Acid; D001418:Baclofen