Experimental study of denervated rat muscle. Part I: Histochemical and electrophysiological observations of denervated rat muscle

Abstract

Histochemical and electrophysiological observations were carried out on denervated rat muscles, mainly extensor digitorum longus muscle. The myofibrillar ATPase reaction was employed to classify the type of muscle fibers. Type 1 fiber, low ATPase activity, and type 2 fiber, high ATPase activity, were recognized. It is generally believed that denervation causes a preferential atrophy of type 2 fibers and these fibers may be more dependant on neural influence than type 1 fibers. But the result of this investigation revealed that the atrophy of type 1 fiber and the enlargement of type 2 fiber will be caused by denervation. The term of enlargement is not equivalent to hypertrophy. Enlargement means the increasing of diameter of muscle fiber reacting to the denervation in this experiment. It is deduced that type 1 fiber is affected more by neural control than type 2 fiber.