Objective     To explore high-altitude-adaptation-related mitochondrial proteins by analyzing the differences of gastrocnemius mitochondrial protein profiles between plateau Pika and Wistar rat.      Methods     The plateau Pikas were captured in Kunlun Mountain (4 500 m) while Wistar rats were bred at low altitude (Chongqing

300 m) and exposed to hypobaric hypoxia (4 500 m) for 30 d. After animals of both groups were anesthetized

bilateral gastrocnemius were collected and mitochondria were extracted and purified. Two dimensional electrophoresis and PDQuest were applied and the peptide mass fingerprinting of differential proteins was analyzed with matrix assisted laser desorption/ionization mass spectrometry analysis (MALDI-TOF MS) and Q-TOF（quatropde-time of flight）MS/MS.      Results     Great difference in gastrocnemius mitochondrial profiles of plateau Pika and Wistar rat was found. Among the differential protein spots

11 were identified. Six plateau Pika specific protein spots were identified as ubiquinol-cytochrome c reductase core protein I

creatine kinase

mitochondrial isoform 4

glyceraldehyde-3-phosphate dehydrogenase

creatine kinase

hypothetical protein XP_499518 and a novel protein. Five Wistar rat specific protein spots were identified as subunit d of mitochondrial H-ATP synthase (2 spots)

LOC498909 protein and creatine kinase.      Conclusion     Our results suggest the difference in mitochondrial energy metabolism

antioxidative activity

mitochondrial DNA stability exist between plateau Pika and Wistar rat.