title: Serotonin receptors on submucous neurons in guinea pig colon.
abstract: Intracellular microelectrodes were used to investigate the neuropharmacology of 5-hydroxytryptamine (5-HT) in the submucous plexus of the distal colon of the guinea pig. Three effects resulted from application of 5-HT to submucous neurons. Two of the effects were components of a biphasic depolarization mediated by receptors on the neuronal cell body. The third was suppression of acetylcholine release at nicotinic synapses on the cell bodies and was mediated by presynaptic 5-HT receptors. The initial component of the biphasic depolarization was a rapidly activating response characterized by increased ionic conductance and a tendency for rapid desensitization. Pharmacological analysis with selective agonists and antagonists suggested mediation of this response by the 5-HT3 receptor subtype. The second component of the depolarizing response was a slowly activating and long-lasting depolarization associated with decreased ionic conductance. Analysis of this response suggested it was mediated by the 5-HT1P receptor subtype. Identification of the presynaptic receptors for 5-HT was equivocal. These receptors did not behave like 5-HT3 or 5-HT1P receptor subtypes. The putative 5-HT4 agonist 5-methoxytryptamine was equipotent with 5-HT in producing presynaptic inhibition at the fast nicotinic synapses.
authors.affiliation: Department of Physiology, College of Medicine, Ohio State University, Columbus 43210-1239.
authors.forename: T
authors.initials: T
authors.lastname: Frieling
authors.forename: H J
authors.initials: HJ
authors.lastname: Cooke
authors.forename: J D
authors.initials: JD
authors.lastname: Wood
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D003106:Colon / Q000294:innervation / Q000378:metabolism*; D004594:Electrophysiology; D006168:Guinea Pigs; D007211:Indoles / Q000494:pharmacology; D008297:Male; D009474:Neurons / Q000378:metabolism*; D011985:Receptors, Serotonin / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*; D012702:Serotonin Antagonists / Q000494:pharmacology; D013368:Submucous Plexus / Q000378:metabolism*; D000077526:Tropisetron
chemical_list: D007211:Indoles; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D012701:Serotonin; D000077526:Tropisetron