Some properties of the denervated anterior gracilis muscle of the rat.

1. Microdrops of acetylcholine (ACh) were topically applied to denervated, mammalian skeletal muscle in vivo, and ACh-evoked depolarization and contracture were recorded simultaneously.2. Contracture tension was directly proportional to the degree of ACh-elicited depolarization.3. Atropine and (+)-tubocurarine increased the amount of ACh required to produce a given amount of depolarization, but these anticholinergic agents did not alter the relationship between the degree of ACh-evoked depolarization and contracture tension.4. Topically applied catecholamines did not produce either depolarization or contracture, despite the fact that parenterally administered catecholamines elicited both responses.