Subclassification of peripheral dopamine receptors.

Dopamine receptors in peripheral tissues have been subclassified using agonists and antagonists. The vascular dopamine receptors in the dog and cat mesenteric vascular beds are similar; those in the rabbit isolated splenic artery are similar to those in the human isolated basilar artery, but appear to differ in some respects from those in the mesenteric vascular beds. The dopamine receptors in the chemoreceptor trigger zone of the dog and the neuronal dopamine receptors on the sympathetic nerve terminals supplying the cat heart and nictitating membrane and the dog femoral vascular bed seem to be the same. However they are all clearly different from the vascular dopamine receptors. The neuronal dopamine receptors on the cholinergic nerve terminals of the rabbit rectococcygeus muscle appear different from other neuronal receptors. The results suggest that sub-types of vascular and neuronal dopamine receptors may exist.