Antagonism by tetrahydro-beta-carboline of the vasoconstrictor responses to tryptamine in rat tail arteries.
Tryptamine and 5-HT mediate vasoconstriction in the isolated perfused rat tail artery. These agonists were differentiated by the classical serotonin receptor antagonists methysergide and ketanserin which were significantly more potent against 5-HT-induced responses. Neither prazosin nor RX 781094 alone or in combination reduced the vasoconstriction produced by tryptamine. Tetrahydro-beta-carboline (THBC) was devoid of agonist properties and behaved as a competitive antagonist of tryptamine but not of 5-HT. THBC also had alpha-adrenoceptor blocking properties in this preparation.
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D002243:Carbolines / Q000494:pharmacology*; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011985:Receptors, Serotonin / Q000187:drug effects; D012702:Serotonin Antagonists / Q000494:pharmacology; D014363:Tryptamines / Q000037:antagonists & inhibitors*; D014661:Vasoconstriction / Q000187:drug effects*
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D002243:Carbolines; D007211:Indoles; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D014363:Tryptamines; C030820:tryptamine; C009804:tryptoline