Fig. 4.

Mitochondrial ROS mediate the hypoxia-induced increase in [Ca₂₊]_i. (A and B) ATII cells were treated with 100 μM t-H₂O₂ or vehicle for 10 min in the presence or absence of BAPTA-AM (20 μM, 15-min preincubation) (A) or STO-609 (20 μM, 30-min preincubation) (B), and pAMPKα and total AMPKα were determined by Western blot analysis. Representative Western blots are shown. (C) ATII cells were exposed to 21% (normoxia) or 1.5% (hypoxia) O₂ for 10 min in the presence or absence of EUK-134 (20 μM, 15-min preincubation) or were treated with t-H₂O₂ (100 μM, 10 min). Endogenous STIM1 was detected by immunofluorescence microscopy using an anti-STIM1 antibody. (D to F) Calcium influx into ρ⁰-A549 cells exposed to hypoxia, t-H₂O₂, or thapsigargin (TG). Perfusion was started in Ca²⁺-free medium and switched to 2 mM Ca²⁺ as indicated. Results are from 5 experiments with 17 to 43 cells each.