Increase of Muscle Permeability to Aldolase in Several Experimental Atrophies

Abstract

AFTER denervation the whole sarcolemma becomes as sensitive to acetylcholine as the neuromuscular junction of the normal fibre¹. An increase of the rate of exchange of ²⁴Na and ⁴²K between interior and exterior of the denervated muscle has been observed² and this increase can be attributed to an increase in sarcolemma permeability. From this it could be supposed that denervation would also affect other properties of the sarcolemma. It was, therefore, decided to determine whether the sarcolemma of the denervated muscle showed an increase in permeability to protein molecules, because it is known, mainly from the data of Zierler^3–7, that aldolase, and probably other glycolytic enzymes, moves out of the fibres during incubation of normal skeletal muscle of rat in vitro, probably by diffusion. This work has been extended to other conditions leading to atrophy of the muscle, namely, tenotomy, partial ischæmia and caloric deprivation.