Effects of Catecholamines on Isolated Canine Facial Veins

抄録

The buccal segment of the canine facial vein which was precontracted moderately with prostaglandin F_2α relaxed to different extents in response to dopamine (DA), norepinephrine (NE), epinephrine (Epi) and isoproterenol (Isp). Propranolol (10^-6M) reversed the relaxation responses to contractions. In the presence of an α-adrenoceptor blockade and inhibitors of neuronal and extraneuronal uptakes, the four catecholamines relaxed the vein fully, and the order of pD₂ values was Isp (8.34) > Epi (7.53) ≅ NE (7.50) >> DA (5.31). The results indicate that in the canine facial vein, β-adrenoceptors predominate over α-adrenoceptors, and the subtype of β-adrenoceptor may be the β₁-type.