Evidence that 5-hydroxytryptamine does not mediate GABA-induced contractile responses in the guinea-pig proximal ileum.
Segments of the isolated proximal ileum of the guinea-pig were set up in the organ bath to record longitudinal muscle contractions. Both gamma-aminobutyric acid (GABA) and 5-hydroxytryptamine induced neurally mediated cholinergic contractile responses; desensitization to 5-HT did not consistently depress contractile responses to GABA, whilst quipazine antagonized the neuronal responses induced by 5-HT without affecting responses to GABA. It is thus concluded that 5-HT does not mediate GABA-induced responses in the ileum.
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D005260:Female; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D011814:Quipazine / Q000494:pharmacology; D012701:Serotonin / Q000494:pharmacology*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D012701:Serotonin; D011814:Quipazine; D005680:gamma-Aminobutyric Acid; D000109:Acetylcholine