Effects of adrenaline, dopamine, serotonin, and different cholinergic agents on smooth muscle preparations from the ansa proximalis coli in cattle: studies in vitro.

The effects of adrenaline, dopamine, serotonin, and different cholinergic agents on isolated muscle strips from the ansa proximalis coli in cattle were studied. Adrenaline (5 x 10(-5) mol/l) evoked a relaxing effect (p < 0.05) on longitudinal and circular muscle strips, mediated via beta- and alpha 1-receptors respectively. High concentration of dopamine (5 x 10(-4) mol/l) caused a non-significant inhibitory effect on longitudinal smooth muscles, which was probably mediated by beta- and not by dopamine-receptors. Serotonin (5 x 10(-5) mol/l) and cisapride (75 x 10(-6) mol/l) had no effect. Carbachol (2 or 10 x 10(-6) mol/l) and bethanechol (5 or 10 x 10(-5) mol/l) caused a dose-dependent (p < 0.05) contraction of both smooth muscle types. This excitatory effect was inhibited (p < 0.05) by metoclopramide (1 x 10(-4) mol/l), as well as the muscarinic agents RS-86 (5 x 10(-5) mol/l) and CGP-37,218 (37.5 or 75 x 10(-6) mol/l).