CHOLINERGIC TRANSMISSION AND ACETYLCHOLINE OUTPUT.

Evidence is presented refuting the possibility that pyruvylcholine might be a transmitter in cholinergic transmission processes.The physiology and pharmacology of acetylcholine release is discussed, with special reference to recent work.Experiments on the output of acetylcholine from electrically stimulated ileum preparations are described. It is suggested that two output mechanisms may exist: one important at low firing rates, which yields a constant output of transmitter per unit time and is morphine-sensitive; the other brought in at higher frequencies of excitation, which yields a more nearly constant volley output, and is morphine-resistant.