Ojewole J A
Methods Find Exp Clin Pharmacol. 1984 Mar;6(3):115-8.
The antagonism between acetylcholine and phenoxybenzamine on isolated driven left atria of guinea-pigs has been examined. Phenoxybenzamine (10(-6) and 2.5 X 10(-6)M), added to the bath fluid 5 minutes before the administration of acetylcholine (10(-7) - 10(-6)M), caused an almost parallel shift (to the right) in the log dose-response curve of acetylcholine on isolated driven left atria of guinea-pigs. There was no fall in the maximum attainable response induced by acetylcholine. These results were taken to imply a reversible, competitive antagonism between acetylcholine and phenoxybenzamine in isolated atria of guinea-pigs. It is suggested that phenoxybenzamine probably combines reversibly (like atropine) with the muscarinic cholinoceptors on the atrial muscle to antagonise, in a competitive manner, the inhibitory action of acetylcholine on isolated atrial myocardium.
已对乙酰胆碱与酚苄明在豚鼠离体起搏左心房上的拮抗作用进行了研究。在给予乙酰胆碱（10⁻⁷ - 10⁻⁶M）前5分钟，将酚苄明（10⁻⁶和2.5×10⁻⁶M）加入浴液中，导致乙酰胆碱对豚鼠离体起搏左心房的对数剂量 - 反应曲线几乎平行右移。乙酰胆碱诱导的最大可达到反应没有下降。这些结果表明在豚鼠离体心房中乙酰胆碱与酚苄明之间存在可逆的竞争性拮抗作用。提示酚苄明可能像阿托品一样与心房肌上的毒蕈碱型胆碱受体可逆性结合，以竞争性方式拮抗乙酰胆碱对离体心房心肌的抑制作用。
