Enhanced Protein Synthesis in a Cell-Free System from Hypertrophied Skeletal Muscle

Hamosh, Margit; Lesch, Michael; Baron, Jeffrey; Kaufman, Seymour

doi:10.1126/science.157.3791.935

Cited by 71 publications

(33 citation statements)

References 15 publications

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“…Although Goldberg et al (1975) found no change in protein synthesis of skeletal muscle after electrical stimulation in vitro, Peterson & Lesch (1972) observed an increased incorporation of amino acids into proteins of the papillary muscle of the heart after repeated stimulations. Also in keeping with the present study Hamosh, Lesch, Baron & Kaufman (1967) found increased rates of protein synthesis during work-induced hypertrophy of skeletal muscle.…”

Section: Discussionsupporting

confidence: 77%

“…The increase in RNA concentration in response to activity (Fig. 3) is in agreement with the higher RNA concentrations, RNA polymerase activities and rates of RNA synthesis in hypertrophying muscles (Hamosh et al 1967;Sobel & Kaufman, 1970;Jablecki, Hauser & Kaufman, 1973). Further, the initial stimulation of protein synthesis by the return of normal activity appears to be dependent upon the synthesis of new RNA, rather than merely a more efficient utilization of existing RNA molecules (Table 1).…”

Section: Discussionsupporting

confidence: 69%

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The influence of activity on muscle size and protein turnover.

Goldspink¹

1977

The Journal of Physiology

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1. The effects of the loss of normal activity can be studied in muscles held in a shortened position by immobilizing the ankle in a plaster cast. Since the innervation remains intact with this procedure, removal of the restraining case allows normal activity to be restored. The soleus and plantaris muscles grew as a function of time after the return of normal activity and these changes in tissue size are explained by changes in the average rates of protein synthesis and protein break‐down as measured by sensitive in vitro techniques. Activity stimulates protein synthesis and inhibits protein break‐down of the soleus muscle, thus enabling the tissue to accumulate protein. Blockage of de novo synthesis of RNA, but not DNA, severely restricted the normal, rapid enhancement of protein synthesis after thr return of activity. 2. The return of isotonic activity to the extensor digitorum longus muscle after immobilization in a lengthened position failed to fully compensate for the loss of the growth‐promoting influence of stretch and the tissue gradually returned to the size of the control muscle. During the recovery process the higher rate of protein turnover and RNA concentrations of the immobilized muscle returned to the lower values of the control.

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Section: Discussionsupporting

confidence: 77%

Section: Discussionsupporting

confidence: 69%

The influence of activity on muscle size and protein turnover.

Goldspink¹

1977

The Journal of Physiology

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“…Furthermore, this fat-mobilizing effect, which persists for a considerable time after the cessation of exercise (15,16), could play a role in the conservation of lean tissue by making available to muscle and organ cells more of the energy stored as fat. The greater lean body mass of the exercising animals, as compared with the sedentary, food-restricted controls, could also reflect stimuli for amino acid conservation and protein synthesis, such as a direct effect of exercise on muscle (18) and the anabolic effects of increased levels of growth hormone secretion secondary to the exercise (19). (5), using the formula of Entenman, Goldwater, Ayres, and Behnke (2), on eight obese subjects who were on a restricted food intake for 12 wk (61%).…”

Section: Discussionmentioning

confidence: 99%

Effects of weight changes produced by exercise, food restriction, or overeating on body composition

Oscai¹,

Holloszy²

1969

J. Clin. Invest.

120

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A B S T R A C T The body weight of rats was reduced by exercise or by restriction of food intake over a period of 18 wk. Body composition was studied to determine if exercise protects against the loss of lean tissue that can occur as a result of a negative caloric balance.Rats weighing 706 ±14 g were divided into four groups matched for weight. A baseline group was killed at the beginning of the study. An exercising group, fed ad lib., was subjected to a program of swimming. A sedentary, free-eating group was provided with food ad lib. Two sedentary, paired-weight subgroups were calorie restricted so that they lost weight at the same rate as the exercisers. The protein intake of one pairedweight subgroup was matched with that of the exercising group. The other sedentary, paired-weight animals ate the standard diet.There was no significant difference in body composition between the two sedentary, paired-weight subgroups which were, therefore, pooled for comparison with the other groups. The exercisers lost 182 ±19 g as a result of both an increase in caloric expenditure and a decrease in appetite. The sedentary, food-restricted animals lost an average of 182 ±18 g. The sedentary, freeeating animals gained 118 ±13 g. The carcasses of the exercised animals contained significantly less fat and more lean tissue than those of the sedentary, pairedweight animals, providing evidence for a fat mobilizing and protein conserving effect of exercise. The composition of the body substance lost by the exercising animals was 78% fat, 5% protein, 1% minerals, and 16% water, compared to 62% fat, 11% protein, 1% minerals, and 26% water for the sedentary, food-restricted rats.

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“…For example, the metabolic capacity of muscles is affected specifically by the type of exercise training [1][2][3]. Increased activity or over-loading by removing the synergists causes a compensatory hypertrophy [4][5][6][7][8][9][10][11]. Hypertrophy is also induced by the stretching of matured muscles in vivo [12,13] and cultured myotubes and fibroblasts [14][15][16][17].…”

mentioning

confidence: 99%

Neuromuscular Adaptation to Microgravity Environment.

Ohira

2000

JJP

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The pattern of muscle activity influences the morphological, metabolic, and contractile properties of skeletal muscles. For example, the metabolic capacity of muscles is affected specifically by the type of exercise training [1][2][3]. Increased activity or over-loading by removing the synergists causes a compensatory hypertrophy [4][5][6][7][8][9][10][11]. Hypertrophy is also induced by the stretching of matured muscles in vivo [12,13] and cultured myotubes and fibroblasts [14][15][16][17]. Exercise-induced metabolic adaptation of muscles is lost when exercise training is stopped [18]. Further, muscle atrophy is induced by denervation [10,19], spinal cord transection [20], joint immobilization [21][22][23], tenotomy [24,25], spaceflight [26][27][28][29], and/or hindlimb suspension [29][30][31][32]. Most of these models are generally presumed to be models of reduced neuromuscular activity. But the level of use may not be the only factor involved in the atrophic process.There is a close association in the physiological, biochemical, and morphological properties between a motoneuron and the muscle fibers it innervates [1]. Studies to support this view are those in which chronic electrical stimulation at low frequency (1-10 Hz) changes the properties of fast-twitch muscles toward those of slow-twitch muscles [33][34][35][36][37][38].Some of the characteristics of muscle fibers are also altered following cross-innervation [39][40][41][42]. Buller et al. [40] suggested that the neural influence on muscle could be due to neurotrophic effect as well as via nerve impulses. Muscular Responses to Gravitational Unloading Morphological propertiesGravitational unloading by exposure to weightlessness [26][27][28][29][43][44][45][46][47] and/or its simulation model, hindlimb suspension [29][30][31][32][48][49][50][51][52][53][54][55][56], causes rapid atrophy in muscles, such as soleus and adductor longus, that are composed predominantly of slow fibers. The cross-sectional areas (CSAs) of both slow-and fasttwitch fibers of rats were less after 14 d of spaceflight and hindlimb suspension than those in the agematched controls [29]. But the degree of atrophy was greater in slow-than fast-twitch fibers [28,29]. Therefore, muscles composed of predominantly slow fibers are more susceptible to atrophy [26,28, 47]. The weights of fast-twitch ankle dorsi-flexors, such as the tibialis anterior (TA) and extensor digitorum longus (EDL), are also generally less after unloading than those of age-matched controls [31, 57]. But these were Japanese Journal of Physiology, 50, 303-314, 2000 Key words: atrophy, fiber-type transformation, contractile properties, neural responses, microgravity.Abstract: Morphological and/or functional characteristics of skeletal muscles have a greater adaptability in response to changes in environmental stimuli. For example, an atrophy associated with a shift of fiber characteristics toward fast-twitch type is a common adaptation of antigravity muscle to a microgravity environment. Neuromuscular responses and ...

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Enhanced Protein Synthesis in a Cell-Free System from Hypertrophied Skeletal Muscle

Cited by 71 publications

References 15 publications

The influence of activity on muscle size and protein turnover.

The influence of activity on muscle size and protein turnover.

Effects of weight changes produced by exercise, food restriction, or overeating on body composition

Neuromuscular Adaptation to Microgravity Environment.

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