Effect of a cholinergic stimulant on interaction of isoprenaline with beta-adrenoceptors.
The maximum contraction induced in taenia from the guninea pig caecum by a cholinergic stimulant, butyltrimethylammonium (BuTMA) was relaxed by papaverine (10(-4) M) but not by l-isoprenaline (5 X 10(-7) M). The concentrations used relaxed the taenia completely in the absence of BuTMA. BuTMA (10(-4) M) decreased the increase of cyclic AMP caused by isoprenaline but not that due to papaverine. Futhermore, photoinactivation of the beta-adrenoceptors by l-isoprenaline was not observed on the taenia contracted by BuTMA (10(-4) M). These results suggest that l-isoprenaline does nto interact with the beta-adrenoceptors in the taenie contracted by the high concentration of BuTMA.
D000818:Animals; D002432:Cecum / Q000187:drug effects / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D004347:Drug Interactions; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D010277:Parasympathomimetics / Q000494:pharmacology*; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D011941:Receptors, Adrenergic / Q000187:drug effects*
D010277:Parasympathomimetics; D000644:Quaternary Ammonium Compounds; D011941:Receptors, Adrenergic; D000242:Cyclic AMP; D007545:Isoproterenol