Bioelectrical impedance of the left ventricle of the rat heart during physical exercise of different durations

Regular physical exercise causes morphofunctional changes in the heart depending on the load. The aim of our study was to identify changes in the bioimpedance spectroscopy parameters of the left ventricle of the heart in rats after physical exercise (swimming) of different duration. Material and methods. Morphological and bioimpedance assessment of the left ventricle of the heart was performed in male rats that underwent a 12-week swimming course and in intact animals. Two groups of rats were subjected to swimming (5 times a week): the experimental (200 minutes a day) and the control (5 minutes a day). Results and discussion. Histological studies have shown an increase in the diameter of cardiomyocytes in the left ventricle of the heart in animals of the experimental and control groups compared to intact rats. In animals subjected to prolonged physical exercise, a significant increase in the reactance of the bioelectrical impedance of the left ventricle of the heart at an electric current frequency of 50 kHz was revealed compared to those swimming for five minutes a day, indicating greater changes in muscle tissue volume. An increase in the active resistance of the bioelectrical impedance of the left ventricle of the heart was noted along with a smaller volume of connective tissue in the rats of the experimental group compared to the control. The amplitude of the bioelectrical impedance of the myocardium of the left ventricle of the heart in rats of the experimental group was greater than in animals of the control (at 30 and 50 kHz) and intact (at 100 kHz) groups, which indicates differences in the volume of intercellular and intracellular space. Conclusions. In rats under the influence of prolonged physical exercise by swimming for 12 weeks, morphometric and bioimpedance changes in the left ventricle of the heart associated with physiological remodeling of the myocardium were revealed.