The Gravity and Protein Metabolism of Skeletal Muscles in Japanese Quail. In vivo and in vitro Comparison

J ankela J .• M. B aranovska: The Gravity and Protein Metabolism of Skeletal Muscles in Japanese Quail. In vivo and in vitro Comparison. Acta vet. Brno 1996.65: 77-81. The aim of the experiment was to observe the effect of increased gravitational field (2 g) on the synthesis and degradation rates of skeletal muscles proteins in Japanese quail. The observations in vivo were compared with results obtained on the isolated muscles. The rates of synthesis and degradation of mixed proteins in m. biceps brachii and m. iliotibialis anterior were estimated. It was shown. that the protein synthesis rates only in in vivo experiment were affected. A decrease of protein degradation rates in both conditions were observed. 2 g hypergravity, protein synthesis and degradative rates, effect in vivo, in vitro For determination of the capacity of muscles to cope with the load of gravitational stress it is important to understand the influence of altered gravity. Our earlier results (G a f 0 et al. 1988; Jan k e I a et al. 1991) confirmed that altered gravity caused changes in muscle mass connected with changes in protein level and composition. It is anticipated that muscle growth or atrophy is regulated by the changes in protein synthesis or degradation (Van den bur g h 1987). We paid attention to quantification of these processes. To eliminate the possible effect of neurohumoral mechanisms. the observations in vivo were compared with results of experiment in which isolated muscles were used. Materiats and Methods In vivo experiment 42 days old japanese quail cockerels were used. The control birds were kept under normal husbandry conditions (24 hours lighting. ambient temperature 21 ·C, commercial mash ad libitum). The experimental treatment of increased gravitational field (2 g) was administered for 144 hours continually by means of centrifuge. Parameters are given in Gato et al. (1988). During the centrifugation the feed supply. lighting and temperature were the same as in the control group. Centrifugation was interrupted only for a few minutes one hour before finishing the centrifugation. the label C14 arginine was peritoneally injected. Breast (m. supracoracoides) and thigh (m. superficialis fibularis) muscles were removed and analysed for protein (L 0 wry et al. 1957), RNA and DNA (Canev and Markov 1960) contents. The parts of muscles were homogenised in 10% trichloroacetic acid and the sediments were hydrolysed. In supernatants as in hydrolysates the arginine concentration and its radioactivity after thin layer chromatography were estimated. The arginine measurement was according the method of Sakaguchi (Devenyi and Gergely 1974). The radioactivity was measured by means of Packard TriCarb liquid scintillation system. In vitro experiment The wing (m. biceps brachii) and tight (m. iliotibialis anterior) muscles of 42 days old Japanese quail-cockerels. were incubated in the Krebs-Henseleit solution bubled with carbon dioxide oxygene mixture and centrifuged to 2 g for one hour. For synthetic rate measurement the C14 arginine was added into the solution. The muscles were analysed for arginine concentration and radioactivity by the methods mentioned above. For the determination of the degradafive rate the inhibitor of protein synthesis (actinomycine) was added into incubation solution. The estimation of degradative rate was established on the measurement of loosed thyrosine in that solution. The thyrosine measurement was according the method ofU denfriend and Cooper (1952). The determination of protein synthesis rates were based on the calculations of the specific activities of protein bound and free arginine. in breast and thigh muscle in first experiment or in isolated wing and thigh muscle in the second. Protein degradation was calculated as a difference between synthetic and growth rates (M u ram a t suet al. 1985) in in vivo experiment. In isolated muscles the determination of degradative rate was established on the measurement of loosed thyrosine after inhibition of protein synthesis.