The role of prostaglandins in cholinergic neurotransmission in the guinea pig.

Prostaglandins have contrasting effects on neurotransmission at different cholinergic nerve endings. This is a report on the role of prostaglandins in a number of cholinergic preparations from the guinea pig. In the isolated ileum PGE1 (2 X 10(-10) to 5 X 10(-8) M) potentiated the response to electrical stimulation of the cholinergic nerves. PGE1 (10(-7 M) caused an increase in tone followed by a period of transient inhibition of twitch height. Responses to simulation of the ileum with drugs were not potentiated by PGE1. Responses of atropinized or plexus-free muscle to electrical stimulation were also not potentiated by PGE1. Acetylsalicylic acid (2.5 X 10(-4) M) diminished the twitch response and the output of acetylcholine from the ileum. Both effects were reversed by PGE1. Qualitatively similar observations were made on the trachea. It is concluded that prostaglandins facilitate acetylcholine release in the ileum and trachea. PGE1 diminished the effect of vagal stimulation on the heart rate. The response to stimulation of the phrenic nerve was not affected.