[Experimental approaches to determining molecular mechanisms of antiarrhythmic and cardioprotective actions of new compounds].

The comparative study of ion homeostatic regulation in the cardiomyocytes in health and in experimental hypoxia showed that the elevated diastolic concentration of free ions of sodium ([Na+]in and calcium ([Ca2+]cyt) in the cardiomyocytic cytoplasm, the lower resting potential of the cell plasma membrane (delta phi n) are major arrhythmogenic agents. The decreased (delta phi n) is mainly defined by lower Na+/K(+)-ATPase activity due to insufficient energy production. The activation of Na+/H(+)-antiport underlies the elevation of [Na+]cyt.