Cardiomyocyte mitochondrial respiration and microviscosity in rats of different ages in heart failure

Abstract

Highlights. Heart failure in older age groups is an urgent medical and social issue. Mitochondrial dysfunction is a key link in the pathogenesis of heart failure. In this study we have demonstrated a decrease in mitochondrial respiratory function in old rats. In this age group, the development of heart failure is accompanied by a further decrease in respiratory control. An increase in the mitochondrial microviscosity in older animals may affect the activity of respiratory chain enzymes in heart failure.Aim. To study the respiratory activity and mitochondrial membrane microviscosity of cardiomyocyte of rats of different ages with heart failure.Methods. The study involved 22 2- and 15-month-old male Wistar rats. The animals were divided into 4 groups: 2 groups of intact animals of both ages (n = 12) and 2 groups of rats with isadrine model of heart failure (HF) (n = 10). HF was modeled by two subcutaneous injections of isoproterenol hydrochloride (170 mg/kg) at interval of 24 hours. Mitochondrial respiratory activity was assessed using respiratory control coefficient. The microviscosity of mitochondrial membranes was evaluated by eximerization coefficients of pyrene-based fluorescent probe in areas of protein-lipid and lipid-lipid contact. Comparative statistical analysis of independent groups was performed using the nonparametric Mann-Whitney test.Results. A decrease in mitochondrial respiratory control in older rats was shown in comparison with young animals. In the HF model, inter-age difference increases, but at the same time, in younger rats, the development of HF is not accompanied by significant changes in mitochondrial respiratory control. An age dependent decrease in the microviscosity of mitochondrial membranes in the area of protein-lipid and lipid-lipid interaction was revealed. In younger rats, the development  of HF is characterized by a significant increase in microviscosity in the area of protein-lipid and lipid-lipid contact. In older rats, the development of the pathology is characterized by a significant decrease in microviscosity in the area of protein-lipid interaction.Conclusion. Multidirectional age-related changes in cardiomyocyte mitochondria of rats with heart failure were revealed. It was shown that mitochondria in younger rats retain their functional activity in the HF model unlike older rats.