Pharmacological characterization of neuronal dopamine receptors in the rat hindquarters, renal and superior mesenteric vascular beds.

The present study was designed to characterize the neuronal dopamine receptors involved in the inhibitory effect of apomorphine on neurogenic vasoconstriction in the isolated autoperfused hindquarters, renal and superior mesenteric vascular beds of the rat. In the three vascular beds, the inhibitory effect of apomorphine on neurogenic vasoconstriction was antagonized by the selective DA2-receptor antagonist domperidone, but not by the selective DA1-receptor antagonist SCH 23390. Local administration of these antagonists had no effect on the perfusion pressure per se or on the pressure response to electrical stimulation of the sympathetic innervation. These results show that the neuronal dopamine receptors present in the rat hindquarters, renal and superior mesenteric vascular beds can be classified as DA2-receptors.