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  • Title: [Effects of adaptation to periodic hypoxia on Ca2+ pump of the cardiac sarcoplasmic reticulum and its resistance to endogenous damaging factors].
    Author: Arkhipenko IuV, Sazontova TG, Rozhitskaia II, Meerson FZ.
    Journal: Kardiologiia; 1992 Jun; 32(6):57-61. PubMed ID: 1405298.
    Abstract:
    The adaptation of rats to periodic "altitude" hypoxia in the altitude chamber (6 hour daily at an altitude of 5000 m during a month) led to increased activity of the Ca2+ pump in the myocardial sarcoplasmic reticulum, which was associated with lower Kd values and higher calcium transport Vmax. When a cardiac homogenate was kept at 4 degrees C, autolysis resulted in a decrease in Ca2+ pump activity (which was more rapid in adapted animals than in the controls) and an equal increase in the levels of free calcium in the homogenates in the two series of experiments. The approximate data were obtained when a homogenate was incubated at 37 degrees C, but when it was incubated at 4 degrees C, the rate of Ca(2+)-pump inactivation decreased 20-fold. Incubation in the presence of free radical oxidative inductors (Fe2+ ascorbate) led to high resistance of myocardial Ca(2+)-pump in the adapted rats. The paper discusses the causes of myocardial Ca(2+)-pump activation in periodic hypoxic adaptation and the mechanisms for its increased resistance to active oxygen, as well as their role in the cardioprotective effect of the adaptation.
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