Introduction of sodium fluoride with drinking water in a dose of 10 mg of fluorine per 1 kilogram of animals mass during a month initiates considerable alterations in tibia’s proteolysis system: total proteolysis activity decreases (substrate caseine, pH 7.6) and activities of cathepsin D (substrate haemoglobin, pH 3.5) and of elastase (synthetic substrate) increases. Introduction of soy-bean isoflavones in a dose of 3 mg/kg normalizes these indices. The preparation of soy-bean isoflavones “EXSO” in a dose of 300 mg/kg has a similar affect.
