Fig. 7. Reduced nuclear accumulation of HIF-1α in episodic hypoxia. (A) Representative Western blot of HIF-1a protein levels in total, nuclear and cytosolic fractions after exposure of DCT cells to different types of hypoxia. Tubulin was used as a cytosolic marker and acetyl histone H3 served as a nuclear marker. (B) Quantitation of HIF-1α protein levels in total cell lysates. Note the stronger increase in HIF1α level in episodic hypoxia relative to 24 h of hypoxia. (C) Nuclear/cytoplasmic ratio of HIF-1α protein levels with normoxia set at 1. While following 24 h of hypoxia HIF-1α predominantly accumulates in the nucleus, episodic hypoxia causes a low nuclear/cytoplasmic ratio. Significance to normoxia #: p<0.05, ##: p<0.01, ###: p<0.001. Asterisks denote significance between hypoxic groups. ***: p<0.001. Error bars indicate standard deviation (n=3).