Summary 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 · 10−5 mol/l) evoked a relaxing effect (p < 0.05) on longitudinal and circular muscle strips, mediated via beta‐ and alpha1‐receptors respectively. High concentration of dopamine (5 · 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 · 10−5mol/l) and cisapride (75 · 10−6mol/l) had no effect. Carbachol (2 or 10 · 10−6 mol/l) and bethanechol (5 or 10 · 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 · 10−4mol/l), as well as the muscarinic agents RS‐86 (5 · 10−5mol/l) and CGP‐37,218 (37.5 or 75 · 10−6 mol/l).

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