FIGURE 1.

STIM1-dependent Ca²⁺ influx in HBECs is inhibited by E2. A, mean changes in Fura-2 emission ratio in polarized HBECs under control conditions or exposed to 10 nm E2 for 15 min. HBECs were placed in bilateral Ca²⁺-free Ringer's and stimulated with 2 μm thapsigargin to monitor ER Ca²⁺ depletion. 2 mm Ca²⁺ was added back to the Ringer's solution on the apical surface only to induce SOCE. B, relative expression of STIM1 or Orai1 after siRNA knockdown, as indicated by quantitative PCR. Nonpolarized HBECs were treated with transfection reagent alone (Ctrl) or transfected with scrambled (Scr) or targeted knockdown (KD) siRNA constructs. C, Fura-2 emission ratio in nonpolarized HBECs that were transfected with scrambled, STIM1, or Orai1 siRNA constructs. SOCE was measured by adding extracellular Ca²⁺ back to the Ringer's solution after ER Ca²⁺ depletion with 2 μm thapsigargin. Data are shown as mean ± S.E.