On the origin and function of the acetylcholine in the intestinal wall

Abstract

This discussion is intended to show that the substances released at nerve endings, he so-called chemical transmitters or mediators, may have additional physio-logical functions independent of nervous activity. During the last two years Lin and I (Feldberg & Lin 1949, 1950) have carried out experiments on the spontaneous release of acetylcholine from the wall of the digestive tract, which appears to be an example of an acetylcholine metabolism of non-nervous origin. Historically we have to go back to the old experiments of Weiland (1912), we Heux (1918-19) and Magnus (1920), who discovered that large amounts of holine are continuously released from the intestinal wall. They, in fact, looked upon choline as the hormone of intestinal movements. Later it was shown that lot only choline but acetylcholine as well is released from the intestinal wall Feldberg & Rosenfeld 1933; Donomae & Feldberg 1934), and that this release continues after degeneration of the extrinsic nerves to the intestine (Bacq & Sroffart 1939). At that time the nerve cells of the myenteric and submucous slexus were considered to be the source of the acetylcholine release. The results of our experiments, however, suggest that the nerve cells in the intestinal wall are arobably not responsible for the acetylcholine release. These experiments are con­cerned with (1) the effect of cocaine on the release of acetylcholine and (2) the listribution in the intestinal wall of the enzyme responsible for its synthesis, the choline acetylase.