Cell culture and hypoxia exposure.

Rat intestinal epithelial cells (IEC)-6 obtained from American Type Culture Collection (Manassas, VA) were cultured with DMEM media (Invitrogen, Carlsbad, CA) containing 10% FBS, 1% penicillin/streptomycin, and 1% glutamate at 37°C in a CO₂ incubator. IEC-6 cells were subjected to hypoxia in a sealed modular incubator chamber (Billups-Rothenberg, Delmar, CA) with 94% N₂-5% CO₂-1% O₂ at 37°C for 20 h. After hypoxia exposure, cells were reoxygenated in a regular CO₂ incubator for another 20 h.