Evidence that dopaminergic innervation is not involved in the vasodilatation of cat superior mesenteric arterial bed: the role of beta-adrenoceptors and circulating catecholamines.

In the presence of phentolamine, stimulation of the cat splanchnic nerve decreased the resistance of the superior mesenteric arterial bed. This effect was not significantly influenced by sulpiride. Sulpiride, in the presence of phentolamine, did not inhibit the decrease in resistance in animals pretreated with guanethidine but propranolol or ablation of the adrenal glands prevented the effect of stimulation. These results are not compatible with the assumption that dopamine released from dopaminergic nerves is involved in the vasodilatation but do provide evidence for the role of beta-adrenoceptors and circulating catecholamines in the vasodilatation of mesenteric vessels.