Changes in total protein and myofibrillar proteinof compensatoy hypertrophied muscle in Rat
Shigeru Yamada, Yoshio Kuroda
I)epartment of Sports Science. Collcgc of r\rts and Sciences,University of Tokyo

Abstract
This study was designed to observe the effect of exercise training on total protein and structuralprotein of muscle by means of the electrophoresis technique. Compensatory hypertrophy was induced in
the soleus and plantaris muscle on one limb by cutting the tendon of the synergistic muscle, the gastrocnemius. The contractile limb received only a sham operation and served as a control. During one
week alter a tenotomy the wet weight of the plantaris of the operated limb was 32fu greater and thatof the soleus was 49!/ greatcr than those of the conrrol muscles. Total protein and myofibrillar protein of muscle werc separated by Na-drxlecyl sulfate (SDS) polyacrylamide electrophoresis. It was demonstrated densography of total protein in muscle thirt some Jraks of the rlensography in hypertrophierlrnuscle indicated high densitl'than those of the control muscles. Some paks of the densography ofmyofibrillar protein in hvpertrophied muscle indicatcd lrigher rlcnsitv rhan in control muscles.

K.! Words: Muscle h)'lertrorhJ,,64 kd frolein, Muscle ,rotein, Fast uuscle, Slotu m scle, Tenotom),Introduction

It was well known that a muscle tissue increase its sttength by exercise training accompaniedwith its hypertrophy. Morpurugo (1875) found that exercise could cause the cross-sectional areas ofthe sartorius muscle to increase without altering the total nrrmber of muscle fibers(r). Helander (1960)
indicated that muscle hypertrophy was usually associated with a increase in the myofibrillar proteinsof the muscles(2). Goldspink (1964) found an increase in the myofibrillar protein in the gastorocnemius rvith a weightlifting exercise program{n). In 1967, Hamosh, reported that the increase in hyper-trophied muscle weight apparently related to increased concentration of RNA in microsomesG) and in1968 it was founrl ttrat rhe hypertrophied muscle 1o contain an increased incorporation of labelledamino acid into the prctein(3)(6). The purfxxe of this study was to determine whether exercise training induced an increase in muscle protein and to observe the qualitatir.e change of total protein andmyofibrillrrr prorein in muscle bv exercise Iraining.

‑64 kaHyp€rtophyHCFig. 3A Electrophoretic prtterns.

Fig. lBA. SI)S polyacrylamide scl electrophoresis of solues musclc total proteini, frorn hyrrrtrophicd

llland control (C] muscles rverc electrophorescd as described in "Methois" and stained rvith Comas.ieblue.

B. Densitometric tracing of electrophoreograms of muscle. Arro\r's indicate the position of 61 Kdprotein.

Weight of soleus and plantaris muscle of the rat increased significantly in 7 days after operation in thepresent study as well. Goldberg (1968) reported that the increase in muscle r.",'eight rvas directly pro'portional rothe incrcase amino acid incorporation and presumably in protein synthesis. Akhough
greater iocorpor^tion oI lmino acid occured both in sarcoplasm and in myo{ibrill proteins, the ralioof myofibriller to soluble counts by radioactivity did not change with hypertrophy. Goldspnrk (1974)
indicated that the proporti(m oI radio:rctivity in substrate extracted from actomyosio system might
be relalerl to increased amount of myofibril during hypertrophy. In the present stucly, there{ore, wc
analyzed the hypertrophy-associ;rted rhanges in muscle structural proteins by means of elcctrophoresis

method. However, the change in trxirl protein and muscle structutal protein in our experimcnts dirl
not direclly contribule to the sludy on these relalions.
The muscle hypcrtrol>hv l)y tenoromy is knrxvn to bc accompanied with decrcase of telanic te'tion output and prolongation of contraction time. (r0)賤瘍￨￨■ ￨彎^●SDS pollacrrlamide gel electrophoresis of total pro-‐ ●●■■●●■■■′.11、 .

‐Fig.,1 l.llectrophoretic parterns.

彎￨

teins in plantaris musclc. Proteins f rom hy|,€rtrophied'■.

■・■‐￨￨￨￨￨￨(H) and control 1C) mLrscles uere electrophoresed￨￨￨￨￨￨￨￨￨￨￨‐ ￨￨as descriLedin "llethoCs" and stained with Comassie

blue.

Fig. 5A lilcctrophoreticpatterns.
‐ ￨￨￨￨‐￨￨￨￨￨￨￨￨￨￨￨￨￨￨￨￨￨￨￨￨￨￨‐￨‐￨￨SDS polyacrylamide gel electrophoresis of structuralproteins in solues muscle. Proteins from hypertro-phied (H) and control (C) musclcs \!crc electro-Hphorcscd as dcscril]cd in "Methods" and stained wiih

Fig. 5AComassie blue.

︱︱︱︱︱︱︱︱
レ

Fig. 58 Structural protein in control muscle.

Fis.58 Structural protein in hypertrophied muscle.

14

l8rnr

CH
Fig. 6 Iilectrophoretic patterns.
SDS polyacrylamide gel electrophoresis of structural proteins ir plantaris mus-cle. Proteins f.om hypertrophied (H) and control (C) musclcs were electrophoresed as described in "Methods" and stained with Comassie blue.

It might Le there{ore suggested that lxrth the decrease of tetanic tensiur output and prolongatiorrof contraction time might be induced by the changes in the hypertrophy-dependent changes in thc
molecular compositions of myofibrillar proteils.
Reference

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15Arn. J. Physiol. 216 : 1111, 1969.

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