Dopamine receptors in the femoral vascular bed of the dog as mediators of a vasodilator and sympathoinhibitory effect.

ET 495 and apomorphine, injected in small doses (0.1--1 microng/kg) into the femoral artery, induced a dose-dependent increase in femoral blood flow. This dilator effect was abolished by section of the ipsilateral femoral nerve and sciatic nerve, transection of the spinal cord, alpha-adrenoceptor blockade, ganglionic blockade and guanethidine. In addition, the increase in blood flow was inhibited by intravenous administration of haloperiol (2 mg/kg i.v.) or pimozide (2 mg/kg i.v.) and by injection of small doses (10--50 microng/kg) of these drugs into the femoral artery. It was concluded that a dopaminergic component located in the femoral vascular bed of the dog may be involved in the local vasodilator and sympathoinhibitory effect of apomorphine and ET 495.