Effects of buphenin on the rat portal vein.
The vasodilator and tocolytic substance buphenin (10 mumol/l) stimulated the spontaneous phasic activity of some (8 out of 18) isolated rat portal vein preparations; 0,1-1 mmol/l buphenin diminished or abolished the activity in all preparations. The isotonic and isometric tonic contractions of portal vein in response to adrenaline, noradrenaline and phenylephrine (0,1-1 mumol/l) disappeared almost completely after addition of buphenin in equimolar concentrations, whereas acetylcholine contractions persisted. The beta-adrenergic blocking agents propranolol and dichloisoprenaline (10 mumol/l) only slightly antagonized the inhibitory effect of buphenin on the contractile responses to catecholamines. It is concluded that buphenin exerts dual action upon rat portal vein: the drug partially stimulates the beta-receptors and partially blocks the alpha-adrenergic receptors.
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D004837:Epinephrine / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009756:Nylidrin / Q000494:pharmacology*; D011169:Portal Vein / Q000187:drug effects; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D013997:Time Factors
D009756:Nylidrin; D011433:Propranolol; D000109:Acetylcholine; D004837:Epinephrine