Activities of cytochrome c oxidase and citrate synthase in lymphocytes of obese and normal-weight subjects

BACKGROUND: Obesity represents a heterogeneous group of disorders associated with broad spectrum of metabolic and endocrine abnormalities. The metabolic changes in obesity may also concern the efficacy of mitochondrial system of energy provision. The aim of our study was to analyse activities of mitochondrial enzymes cytochrome c oxidase (COX) and citrate synthase (CS') in isolated lymphocytes of obese and normal-weight subjects. RESULTS: In the group of 304 non-obese controls, differences between men and women were found neither in the COX and CS activities nor in the COX/CS ratio in isolated lymphocytes. The activity of COX did not change even with age, whereas the activity of CS decreased significantly resulting in age-dependent increase of the COX/CS ratio (P < 0.01). In the group of 60 obese patients aged 17 - 75 y, the COX activity was 1.2-fold higher (P < 0.01) and the CS activity was 1.3-fold lower (P < 0.01) compared to 151 non-obese healthy age-matched controls. Consequently, the COX/CS ratio became 1.7-fold higher (P < 0.01) in the obese patients compared to the non-obese population, which indicates that both the absolute and relative oxidative capacity are increased. CONCLUSION: Isolated lymphocytes from peripheral blood contribute very little to the overall metabolic turnover, but they may serve as easily available marker cells for studying the changes of mitochondrial energy converting systems in obesity.