Acetylcholine-releasing Material in Neural Tissues

Abstract

WHILE examining cholinergic substances in sciatic nerve¹, we noted that acetone extracts of nerve caused a slow contraction of the guinea pig ileum (Fig. 1A). Identical lipid extracts of brain had the same effect (Fig. 1B) ; similar activity could not be detected in kidney, intestine, lung or liver. A salient characteristic of the lipoidal material is that its action is completely blocked by atropine at a dose, 6 ng/ml., that blocked the action of acetylcholine. The lipoidal material causes a slower contraction than does acetylcholine (Fig. 1) ; the material is resistant to acetylcholinesterase, which destroys acetylcholine ; the material retains activity after heating at pH. 10 for 5 min in a boiling water bath, conditions which destroy acetylcholine; the material does not act on a strip of ileum that had been stored either at room temperature for 1 day or at 4° C for 3 days, whereas acetylcholine elicits the usual contractions ; finally, the material is not active on the anoxic ileum, which responds to acetylcholine (Table 1).