Abstract
Using the cannula inserting method, we investigated the vascular responses to norepinephrine (NE), phenylephrine and isoprenaline (Isp) in isolated, perfused simian facial veins. NE usually induced only a vasodilation in nonpreconstricted veins. Phenylephrine consistently induced only a slight vasoconstriction, and Isp produced only a vasodilation. NE-induced vasodilations were reversed to vasoconstrictions after treatment with a relatively larger dose of propranolol. It is concluded that simian facial veins have a spontaneous intrinsic tone and dominant abundant beta-adrenoceptors but sparse alpha1 -adrenoceptors.
