title: Methylxanthines antagonize adenosine but not morphine inhibition in guinea pig ileum.
abstract: In the electrically stimulated guinea pig ileum longitudinal muscle strip preparation the inhibitory actions of adenosine were antagonized by various concentrations of theophylline (12.5 and 100 micro M) and 8-phenyltheophylline (4 and 20 micro M). However, the inhibitory actions of morphine were not antagonized by the same concentration of theophylline and 8-phenyltheophylline. These results suggest that in the guinea pig ileum longitudinal muscle-strip adenosine is not a mediator in the inhibitory actions of morphine.
mesh_terms: D000241:Adenosine / Q000037:antagonists & inhibitors*; D000818:Animals; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D009020:Morphine / Q000037:antagonists & inhibitors*; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D013806:Theophylline / Q000494:pharmacology; D014970:Xanthines / Q000494:pharmacology*
chemical_list: D014970:Xanthines; D009020:Morphine; D013806:Theophylline; D000241:Adenosine