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Effects of Inhibited Neural and/or Mechanical Stimuli on the Water Content and Dry Weight in Rat Hindlimb Muscles.     X.D. Wang¹, M. Danda¹, M. Terada², F. Kawano¹, T. Ohira², Y. Higo², Y. Nakajima³, N. Nakai¹, K. Goto⁴ and Y. Ohira^{1, 2}.  Grad. Sch. of ¹Med. and ²Frontier Biosci., ³Sch. of Sci, Osaka Univ., Toyonaka City, Osaka, and ⁴Toyohashi SOZO Univ., Toyohashi City, Aichi, Japan.

  Effects of tenotomy (T, n=7), denervation (D, n=6), or T+D (n=6) on the water content and dry weight were studied in 19 adult male and female Wistar rats.  The distal tendons of left soleus (Sol), plantaris (Pl), medial and lateral gastrocnemius (MG and LG), tibialis anterior (TA), and extensor digitorum longus (EDL) muscles were cut for T.  The sciatic nerve at the gluteal region was cut off (~1 cm) for D.  The right limb was maintained intact as the normal control.  One or 2 rats with the same treatment were housed in a cage with 35 x 25 cm and 20 cm height).  They were pair-fed (20 g/day) and water was given ad libitum.  After 5 days, these muscles were isolated and wet weight was measured immediately.  Water content and dry weight of the muscle were measured keeping the samples in an incubator kept at 64 ^oC for 3 days.  As the results, the wet weights of all muscles were decreased following each treatment significantly, except in EDL treated with D.  The degree of atrophy in response to T tended to be MG>TA>Sol>Pl=LG>EDL.  That in response to D tended to be Sol>MG=LG>Pl>TA>EDL.  Further, the magnitude of the effect of T+D were Sol>Pl>MG>LG=TA=EDL.  The atrophy of Sol, especially, advanced as T<D<T+D.  Similar patterns were also noted in Pl.  Both absolute water content (mg) and dry weight tended to decrease following these treatments.  But the rates of decrease were similar, being the percent water and dry weights were relatively stable.  It was suggested that both neural and mechanical stimuli play the essential roles in the regulation of skeletal muscle mass. 

  (Supported by the Grant-in-Aid for Scientific Research (S, 19100009) from Japan Society for the Promotion of Science)