Differing actions of beta-(2-thienyl)-gamma-aminobutyric acid in central and peripheral preparations.
In the guinea-pig isolated ileum, beta-(2-thienyl)-gamma-aminobutyric acid (BTG; 100-500 microM) reversibly and competitively (pA2 = 4.3 +/- 0.1) antagonised the baclofen-induced (5-100 microM) depression of cholinergic twitch contractions, but not that to adenosine or morphine. By contrast, in rat neocortical slice preparations, BTG (100-500 microM) acted as an agonist, abolishing the frequency and amplitude of spontaneous discharges, sensitive to 2-hydroxysaclofen (100-500 microM). BTG exhibits differential actions at GABAB receptors in brain and periphery.
Ong
J
J
Department of Anaesthesia and Intensive Care, University of Adelaide, South Australia.
Kerr
D I
DI
Berthelot
P
P
Vaccher
C
C
Flouquet
N
N
Debaert
M
M
D000818:Animals; D001418:Baclofen / Q000031:analogs & derivatives / Q000494:pharmacology; D001921:Brain / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D018756:GABA Antagonists; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D011963:Receptors, GABA-A / Q000187:drug effects*; D013329:Structure-Activity Relationship; D013876:Thiophenes / Q000494:pharmacology*; D005680:gamma-Aminobutyric Acid / Q000031:analogs & derivatives* / Q000494:pharmacology
D018756:GABA Antagonists; D011963:Receptors, GABA-A; D013876:Thiophenes; C078674:4-amino-3-(2-thienyl)butanoic acid; D005680:gamma-Aminobutyric Acid; D001418:Baclofen; C057491:2-hydroxysaclofen