Tetrahydroisoquinolines (TIQs) do not act on opiate receptors in the guinea-pig ileum.
The myenteric plexus-longitudinal muscle preparation of the guinea-pig ileum was stimulated with supra-maximal electrical field stimulation at 0.1 Hz. The contractile response was inhibited by salsolinol (1-300 microM) and tetrahydropapaveroline (THP) (3-30 micro M) but not by (cis)-3-carboxysalsolinol. S(-)-Salsolinol was more potent than R(+)-salsolinol. The inhibition by salsolinol and THP was unchanged by naloxone (up to 10 micro M). However, naloxone completely prevented the inhibition induced by normorphine, with a pA2 of 8.66. The results indicate that salsolinol and THP do not interact with opiate receptors in this preparation.
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D007546:Isoquinolines / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects; D009197:Myenteric Plexus / Q000187:drug effects; D009270:Naloxone / Q000494:pharmacology; D011957:Receptors, Opioid / Q000187:drug effects*; D012490:Salsoline Alkaloids / Q000494:pharmacology; D044005:Tetrahydroisoquinolines
D007546:Isoquinolines; D011957:Receptors, Opioid; D012490:Salsoline Alkaloids; D044005:Tetrahydroisoquinolines; D009270:Naloxone; C014843:1,2,3,4-tetrahydroisoquinoline; D000109:Acetylcholine