[Adrenergic mechanism of the stimulation of the small intestine motor activity].

Myoelectrical activity of the duodenum and ileum was recorded in rabbits with implanted electrode. Acute haemorrhage caused either elevation or reduction of the firing rate, the responses being abolished with a combined blockade of alpha- and beta-adrenoreceptors. Beta-adrenoreceptors agonist isoproterenol resulted in a biphasic (decrease-increase) change of the myoelectrical activity which could be abolished with blockade of beta-adrenoreceptors. The character of the small intestine motor responses to acute haemorrhage and isoproterenol infusion depended on the initial level of the intestinal contractile activity. The findings suggest that catecholamines induce a small intestinal motor effect via stimulation of both inhibitory adrenoreceptors and excitatory presynaptic adrenoreceptors.