[Effects of carnitine on respiratory chain and metabolism of oxygen radical in mitochondria of skeletal muscle after exhaustive running in training rat].

The aim of the present study was to investigate the effect of carnitine on function of respiratory chain and metabolism of oxygen radical in mitochondria of skeletal muscle after exhaustive running in training rats. Forty male Wistar rats were randomly divided into 4 groups (n = 10): control, carnitine, training and training + carnitine groups. The training and training + carnitine groups received 6-week treadmill training, whereas carnitine and training + carnitine groups were administered intragastrically with carnitine (300 mg/kg per day, 6 d/week) for 6 weeks. After exhaustive running, all the rats from 4 groups were sacrificed to obtain quadriceps muscles samples, and muscle mitochondria were extracted by differential centrifugation. Spectrophotometric analysis was used to evaluate activities of respiratory chain complexes (RCC) I-IV, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and the content of malondialdehyde (MDA) in the skeletal muscle mitochondria. The results showed that, compared with the control group, the carnitine group exhibited increased RCCI and RCCIII activities (P < 0.05), the training + carnitine group exhibited increased RCCI, RCCIII and RCCIV activities (P < 0.05 or 0.01). Moreover, RCCIII activity in the training + carnitine group was higher than that in training group (P < 0.05). Compared with the control group, the carnitine, training and training + carnitine groups showed increased SOD activities ( P < 0.01), the carnitine and training + carnitine groups showed increased GSH-Px activities ( P < 0.01), the carnitine, training and training + carnitine groups showed increased MDA contents (P < 0.05 or 0.01). The SOD and GSH-Px activities in training + carnitine group were higher than those in training group (P < 0.01), and the MDA level in the training + carnitine group was higher than that in the carnitine and training groups (P < 0.01). These results suggest that training and carnitine can increase function of respiratory chain, antioxidation and lipid peroxidation tolerance capacity in skeletal muscle mitochondria, and the improving effects of training and carnitine are synergistic.