Abstract: Objective To observe the effect of Xiaoyingqiangji decoction on mitochondria in skeletal muscle of hyperthyroid myopathy. Methods Healthy Wistar rats were randomly divided into 4 groups: the group of hyperthyroid myopathy were given L-thyroxine intraperitoneal injection for 42 d; Chinese medicine treated group were treated with Xiaoyingqiangji decoction for 30 d after L-thyroxine injection; the saline control group were given saline solution for 30 d after L-thyroxine injection; normal control group were given saline solution. Then the skeletal muscles were obtained and the succinate dehydrogenase (SDH) were measured. The ultrastructural changes were observed with TEM. Results The activity and content of SDH in the group of hyperthyroid myopathy decreased, and the cristae of mitochondria ruptured and even disappeared. After given Chinese medicine, the activity and content of SDH increased, while the mitochondria showed normal ultrastructural appearance. Conclusion Xiaoyingqiangji decoction can improve the function of skeletal muscles in hyperthyroid myopathy by recovering enzyme activity and mitochondria structure.

Key words: hyperthyroidism, myopathy, Xiaoyingqiangji decoction, succinate dehydrogenase (SDH), mitochondria, skeletal muscle, rats