Caprolactam-barbiturate interaction at the GABAA receptor complex in the guinea-pig intestine.
4,6,6-Trimethylcaprolactam antagonised GABAA receptor-mediated contractile responses in guinea-pig isolated ileum, displacing the GABA dose-response curve to the right in a non-parallel manner, and causing a depression of the maximum response. Pentobarbitone not only potentiated the GABAA receptor-mediated contractions but also reversed this non-competitive antagonism by 4,6,6-trimethylcaprolactam, shifting the dose-response curve for GABA to the left and restoring the maximum response. It is conclude that this caprolactam acts at the picrotoxin-barbiturate site on the Cl(-)-ionophore complex.
D000818:Animals; D001381:Azepines / Q000494:pharmacology*; D001463:Barbiturates / Q000494:pharmacology*; D002209:Caprolactam / Q000494:pharmacology*; D005260:Female; D018756:GABA Antagonists; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D010424:Pentobarbital / Q000494:pharmacology; D011963:Receptors, GABA-A / Q000187:drug effects*; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D001381:Azepines; D001463:Barbiturates; D018756:GABA Antagonists; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid; D002209:Caprolactam; D010424:Pentobarbital