Potent inhibitory GABAB receptors in stimulated guinea-pig taenia coli.
gamma-Aminobutyric acid (GABA, half-maximal inhibitory concentration, IC50 = 9.9 microM) and (-)-baclofen (IC50 = 4.5 microM) but not 10(-4) M muscimol, exerted a presynaptic inhibitory effect on cholinergic transmission in field-stimulated guinea-pig taenia coli preparations, in vitro. The antagonism by 10(-5) M (1S, 9R)-bicuculline methiodide was not specific for GABA agonists. The results suggest that the GABA receptors involved were of type B.
Rónai
A Z
AZ
Central Research Institute for Chemistry, Hungarian Academy of Sciences, Budapest.
Kardos
J
J
Simonyi
M
M
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001418:Baclofen / Q000494:pharmacology; D001640:Bicuculline / Q000494:pharmacology; D003106:Colon / Q000187:drug effects; D004558:Electric Stimulation; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009118:Muscimol / Q000494:pharmacology; D009130:Muscle, Smooth / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology; D011963:Receptors, GABA-A / Q000187:drug effects*
D011963:Receptors, GABA-A; D009118:Muscimol; D001285:Atropine; D001418:Baclofen; D000109:Acetylcholine; D009638:Norepinephrine; D001640:Bicuculline