Effect of inactivity and passive stretch on protein turnover in phasic and postural rat muscles

Abstract

GOLDSPINK. Effect of inactivity and passive stretch on protein turnover in phasic and postural rat muscles. J. Appl. Physiol. 61(l): 173-179, 1986.-A state of hypokinesia and hypody-namia has been induced in the hindlimb muscles of the rat (100 g) using a suspension model. The ensuing muscle atrophy was assessed by reference to muscles in fully mobile control animals, which were either fed ad libitum or fed the same lower food intake of the suspended animals. Over a total of 7 days of suspension the slow-twitch postural soleus muscle underwent a much greater atrophy than the fast-twitch phasic extensor digitorum long-us. Changes with respect to the position of the suspended foot, and hence muscle length, necessitate caution in comparing the extent of the atrophy between different mus-cle types. After 3 days of inactivity the atrophy of the soleus muscle was explained by a 21 % decrease in the fractional rat