Chronic hypoxia led to the activation of apoptotic signaling cascade.

(A) Representative western blots for expression of CHOP/GADD153 from the cytoplasmic extracts of skeletal muscle. (B) Semiquantitative analysis of the expression of ER associated degradation, CHOP/GADD153. GAPDH considered as the loading control. The densitometric analysis is shown as mean with standard error (bars) performed in n = 3 independent experiments. Specific colorimetric peptide substrate has been used for particular caspases in cellular fuction. Activity of caspase-3 and caspase-9 was measured using colorimetric substrate Ac-Asp-Glu-Val-Asp p-Nitroaniline and Ac-Leu-Glu-His-Asp-pNA. The cysteine protease activity of (C) Caspase-3 and (D) Caspase-9 cleaves the substrate and releases pNA, the absorbance of which can be measured at 405 nm, and the (E) Annexin-V was measured by ELISA kit. All values presented as mean ± SEM. *p<0.05 Vs. Control; **p<0.01 Vs. Control; ***p<0.001 Vs. Control.