MPO and rheumatoid arthritis: During OA, neutrophildegradation results in the discharge of enzymes leading to oxidative stress andrespiratory bursts.54 Thus, increased MPO in inflamed rheumatoid arthitis (RA) cartilage isconnected with the persistent development of disease.55 In mitochondrial aerobic respiration, the electron transport is linked viathe inner mitochondrial membrane throughout four enzyme complexes (I–IV) withcomplex V (ATP synthase) from ADP.56 In the present study, in healthy and OA rats, mitochondrial function wasevaluated by analyzing some complex enzymes of the respiratory chain II, IV, andΔΨm.