Bcl-2/Bax protein expression in heart, slow-twitch and fast-twitch muscles in young rats growing under chronic hypoxia conditions.

Abstract : We have studied the magnitude of apoptosis in heart, slow-twitch skeletal muscle (soleus) and fast-twitch skeletal muscle (gastrocnemius) of rats exposed to 3 weeks in vivo chronic hypoxia. Apoptosis was evaluated biochemically by DNA laddering and by TUNEL and annexin V-staining. The expression of Bax and Bcl-2 proteins was determined by immunohistochemistry and Western blotting. Western blot analysis revealed only a slight difference in Bax expression among the different tissues under normoxic and hypoxic conditions; therefore we can consider that Bax protein is constitutively expressed in muscle tissues. However a singular pattern of Bcl-2 expression was observed among the different tissues under normoxic conditions. Bcl-2 protein was more expressed in fast-twitch glycolytic muscles than in slow-twitch or oxidative muscles with a highest value found in gastrocnemius (4926 +/- 280 AU), followed by soleus (2138 +/- 200 AU) and a very low expression was displayed in the heart muscle (543 +/- 50 AU). After exposure to hypoxia for 21 days (10% O2), Bcl-2 protein expression markedly increased, (44%) in gastrocnemius, (323%) in soleus and (1178%) in heart, with significant differences (p < 0.05 student t-test), reaching a similar threshold of expression in both types of muscles. Furthermore, no sign of apoptosis was detected by TUNEL assay, annexin V-binding assay or DNA electrophoresis analysis. The latter suggested some indiscriminate fragmentations of DNA without apoptosis. In conclusion, we postulate that these protein modifications could represent a adaptative mechanism allowing a better protection against the lack of oxygen in oxidative muscles by preventing apoptosis.
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Article dans une revue
Molecular and Cellular Biochemistry, Springer Verlag, 2001, 226 (1-2), pp.9-16
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Soumis le : samedi 6 juin 2009 - 13:50:36
Dernière modification le : mardi 9 juin 2009 - 11:29:51

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  • HAL Id : inserm-00392265, version 1
  • PUBMED : 11768244

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Catherine Riva, Céline Chevrier, Nicolas Pasqual, Valdur Saks, André Rossi. Bcl-2/Bax protein expression in heart, slow-twitch and fast-twitch muscles in young rats growing under chronic hypoxia conditions.. Molecular and Cellular Biochemistry, Springer Verlag, 2001, 226 (1-2), pp.9-16. 〈inserm-00392265〉

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