Ciliary Movement and Acetylcholine

Acetylcholine is established as a substance which is released at nerve terminations to initiate the contractions of skeletal muscle and to augment the contractions of some forms of smooth muscle. Evidence has also been obtained that the capacity of the isolated auricles of the rabbit heart for maintaining rhythmic activity is closely related to the rate of synthesis of acetylcholine within the auricles (Bulbring and Burn, 1949), and thus the suggestion has arisen that acetylcholine may act as a local hormone to maintain rhythmic movement. The work of Feldberg and Lin (1950) indicates that the formation of acetylcholine in the intestine maintains pendular movement and mucous secretion. If acetylcholine, in addition to being the humoral transmitter of nervous impulses, is also a substance which controls rhythmic movement in various types of muscle, then it might be possible to demonstrate that the activity of the ciliary epithelium is related to acetylcholine production. To test this suggestion we have carried out experiments on the ciliary movement in the oesophagus of the pithed frog and also in the excised trachea of the rabbit.