The inhibitory effect of dopaminomimetics on nerve stimulation-induced vasoconstriction of the cat's carotid artery.

The experiments were carried out in cats anaesthetized with chloralose and urethane. The preganglionic sympathetic nerve was stimulated and blood flow in the common carotid artery and the contractions of the nictitating membrane were recorded. Three intravenously given dopaminomimetics inhibited the vasoconstriction and nictitating membrane contractions induced by nerve stimulation. The rank order of the drugs was: bromocriptine greater than apomorphine greater than piribedil. The relative potencies on carotid blood flow were 100:30:3.1, respectively. The presynaptic site of activity was discussed.