Abstract
We have already reported that picric acid (1, 2) and phenyl acetate (3) provoke a contraction of the guinea pig ileum through acetylcholine liberation from the cholinergic nerve ; the effect of picric acid is inhibited by morphine but the response to phenyl acetate is not affected by morphine. So we speculated that two mechanisms could be responsible for the acetylcholine liberation: one is concerned with the actions of 5-hydroxytryptamine and picric acid and is affected by morphine, the other is brought in the action by phenyl acetate and is resistant to the inhibitory action of morphine (3). In this report the mechanisms concerned with acetylcholine liberation from the cholinergic nerve element of guinea pig ileum are studied, using strychnine, derivatives of phenyl acetate, catecholamines and reserpine.
