Related Experiment Video
Updated: Aug 14, 2026

Contractility Measurements on Isolated Papillary Muscles for the Investigation of Cardiac Inotropy in Mice
Published on: September 17, 2015
Effect of a cholinergic stimulant on interaction of isoprenaline with beta-adrenoceptors
Abstract:
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.
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