title: Comparative effects of somatostatin and enkephalins on the guinea pig ileum and the rat vas deferens.
abstract: The action of somatostatin (SRIF (somatotrophin release inhibiting factor)) was compared with that of Met-enkephalin (Tyr-Gly-Gly-Phe-Met) in the electrically stimulated guinea pig ileum myenteric plexus longitudinal muscle and with that of an enkephalin analogue (FK 33-824 (Tyr-D-Ala-Gly-MePhe-Met-(O)-ol)) in the rat vas deferens. In both tissues SRIF produced a twitch inhibition which was not antagonized by naloxone and which showed a long-lasting tachyphylaxis. The enkephalins tested produced a naloxone-antagonizable inhibition of twitch in both tissues but no tachyphylaxis. Therefore we conclude that SRIF is not acting at opiate receptors in these tissues.
mesh_terms: D000818:Animals; D004723:Endorphins / Q000494:pharmacology*; D004745:Enkephalins / Q000494:pharmacology*; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D009270:Naloxone / Q000494:pharmacology; D009294:Narcotics / Q000494:pharmacology; D051381:Rats; D013004:Somatostatin / Q000494:pharmacology*; D013997:Time Factors; D014649:Vas Deferens / Q000187:drug effects
chemical_list: D004723:Endorphins; D004745:Enkephalins; D009294:Narcotics; D009270:Naloxone; D013004:Somatostatin