Abstract
The nicotinic action of acetylcholine was studied from the view point of the haemodynamic effect and the plasma catecholamine concentration in dogs. The blood pressure and heart rate were measured at 0.5 min after intravenous injection of adrenaline (1μg/kg) and acetylcholine (1, 125, 250, 500μg/kg) with pretreatment of atropine (2mg/kg) in anesthetized dogs. The blood samples were collected from femoral vein at 0.5 min after drug administration. The plasma concentration of adrenaline and noradrenaline was measured by using Liquid chromatography. The blood pressure, heart rate and catecholamine concentration were increased with increase in dose of acetylcholine. After bi-lateral adrenolectomy, there were no changes in blood pressure and plasma catecholamine by acetylcholine (500μg/kg) . It is confirmed that the rise in blood pressure by nicotinic action with acetylcholine after pretreatment of atropine is mainly due to the release of adrenaline from adrenal medulla.
