[Changes in the contractile properties of tonic muscle fibers following denervation].

After denervation, most of the tonic muscle fibers, contrary to intact fibers, cannot keep for a considerable time either the potassium (K) or the acetylcholine (A) contracture. The maximal mechanical tension in response to K and A in the denervated tonic fibers is lesser than in normal. The amplitude, speed of development, and latency (L) of the caffeine contracture remain practically the same. The speed of development of the K contracture sharply falls down and its L rather increases while the respective parameters of the A contracture practically do not change. The main changes developing after the denervation seem to occur in the processes controlling relaxation of the tonic fiber, as well as in the mechanisms for activation of K contracture while preserving the mechanisms for activation of A contracture.