Hypoxia Affects Mitochondrial Protein Expression in Rat Skeletal Muscle

Hypoxia affects mammalian mitochondrial function, as well as mitochondria-based energy metabolism. The detail mechanism has not been fully understood. In this study, we detected protein expression levels in mitochondrial fractions of Wistar rats exposed to hypobaric hypoxia by use of proteomic methods. Adult male Wistar rats were randomized into an hypoxic (4,500 m, 30 days) group and a normoxic control group (sea level). Gastrocnemius muscles mitochondria were extracted and purified. Mitochondrial oxygen consumption was measured with a Clark oxygen electrode; mitochondrial transmembrane potential was detected with Rhodamine 123 as a fluoresce probe. Using 2-DE and MALDI-TOF MS analysis, we identified eight mitochondrial protein spots that were differentially expressed in the hypoxic group compared with the normoxic control. These proteins included Chain A of F1-ATPase, voltage dependent anion channel 1 (VDAC), hydroxyacyl Coenzyme A dehydrogenase alpha-subunit, mitochondrial F1 complex gamma-subunit, androgen-regulated protein and tripartite motif protein 50. Two of the spots, VDAC and ATP synthase alpha-subunit, were confirmed by Western blotting analysis. Oxygen consumption during State 3 respiration, as well as the respiratory control ratio (RCR) was significantly higher in the control than that in the hypoxic group; mitochondrial transmembrane potential was significantly higher in hypoxic group than that in the control. With successful use of multiple proteomic analysis techniques, we demonstrates that 30 days hypoxia exposure has effects on the expression of mitochondrial proteins involved in ATP production and lipid metabolism, decrease the stability of mitochondrial membrane, and affect the mitochondrial electron transport chain.