Hypertrophy and regression of rat heart: free radical related metabolic systems

The ‘high altitude’ intermittent adaptation of rats in a low-pressure chamber induces heart hypertrophy which is especially pronounced in the right ventricle. This increases the right ventricle weight to body weight ratio (RV/B). For the estimation of prooxidant/antioxidant balance the following parameters were measured in hypertrophied and regressing right ventricles: the concentration of lipid peroxidation products, the rate of lipid peroxidation in tissue homogenates induced with Fe2++ascorbate, the activities of the antioxidant enzymes catalase, superoxide dismutase, glutathione reductase, glutathione peroxidase and concentrations of total, protein and non protein thiol levels. It was shown that after adaptation the concentrations of breakdown products of lipid peroxidation, the rate of induced lipid peroxidation, the activity of superoxide dismutase and concentrations of thiol groups were significantly increased in comparison to controls. During the regression period all the measured parameters gradually approached control levels. Only the initial rate of lipid peroxidation remained significantly different from the control on the 7th day of regression. It may be concluded that: (a) the lipid peroxidation rate is the most important parameter for estimating the prooxidant/antioxidant status of the cell; and (b) any activation of free radical-dependent reactions inducing lipid peroxidation in the heart in vivo (ischemia and reoxygenation, stress, physical loading etc.), will be much more dangerous to hypertrophied and regressing myocardium compared with normal. Analysis of correlation coefficients between all the measured parameters allows construction of a scheme of relationships between them. Catalase and superoxide dismutase seem to be the most central among the activities measured due to their extensive interconnections with other components.