The effect of catecholamines on ureteral peristalsis in different species (dog, guinea-pig and rat)

Summary

The effects of adrenaline and noradrenaline and of α- and β-receptor blocking agents on electrical and mechanical activity of the pyeloureteral system were investigated in unanaesthetized dogs and guinea-pigs and in isolated preparations of dogs, rats and guinea-pigs. The catecholamines produce, via α-receptors, positive autochthonotropic and chronotropic effects, particularly strong in the natural pacemaker region, and positive bathmo-dromotropic effects in the other sections of the pyeloureter; further they produce inhibitory effects via β-receptors, which are particularly strong in the lower sections, weaker in the proximal sections and nearly negligible on the pacemaker process. Thus the effect of catecholamines on the manifest frequency of ureteral peristalsis is a complex process with two main components: the effect on the pacemaker process itself and the effects on the subsequent sections which determine the degree of conduction block. This general description seems to be valid for all mammals including man, but nervetheless great species differences exist which are mainly due to a) differences in the total sensitivity to catecholamines, b) differences in the degree of differentiation of adrenergic receptors, and c) differences in the basic myogenic activity.