Evidence for more than one type of 5-hydroxytryptamine receptor in the human colon.
The actions of methysergide, a 5-hydroxytryptamine (5-HT) antagonist, have been examined on muscle strips taken from the circular and longitudinal layers of the human colon. Relaxations of the longitudinal muscle to 5-HT were antagonized by concentrations of methysergide known to be selective. Relaxations of the circular muscle to 5-HT were unaffected by similar concentrations of methysergide. Responses of both types of muscle to 5-HT were partially reduced by tetrodotoxin. Furthermore there was evidence for 5-HT receptors in circular colonic muscle which were unaffected either by selective concentrations of methysergide or tetrodotoxin.
D003106:Colon / Q000187:drug effects*; D006801:Humans; D066298:In Vitro Techniques; D008784:Methysergide / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011985:Receptors, Serotonin / Q000187:drug effects*; D012701:Serotonin / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
D011985:Receptors, Serotonin; D012701:Serotonin; D013779:Tetrodotoxin; D011433:Propranolol; D009638:Norepinephrine; D008784:Methysergide; D010646:Phentolamine