RÉSUMÉ

The impact of hypoxic preconditioning and remodeling on the expression of protein kinase B (Akt) in the heart ventricles was investigated. Male Wistar rats, the residents of plains or middle altitude (2100 m above sea level), were exposed to hypoxic preconditioning by "lifting" in the barochamber at the "altitude" of 5.600 m for 3 h. In the right and left ventricles of the heart, Akt protein expression was determined by Western blotting. It has been shown, that hypoxic preconditioning causes the induction of Akt kinase in the ventricles during the period of delayed cardioprotection (1-3 days after preconditioning). Myocardial remodeling induced by chronic hypoxia in middle altitude was associated with elevated Akt expression in the myocardium, more pronounced in the left ventricle. Progression of hypoxic myocardial remodeling, found in a part of the animals, was accompanied by a reduction of the cell hypoxic reactivity, including Akt induction in response to preconditioning. Thus, Akt kinase is involved in the mechanisms of hypoxia induced late preconditioning and myocardial remodeling in chronic hypoxia. Inhibitory regulatory mechanism was found to limit the induction of Akt in myocardium after remodeling.