Figure 4

The effect of STIM1 silencing on hypoxia-induced enhancement of SOC-mediated Ca²⁺influx. After transfection with STIM1 siRNA, PASMCs were cultured in hypoxic conditions for 24 hours. The SOC-mediated PASMC Ca²⁺ influx was measured following stimulation with 10 μM cyclopiazonic acid during the change from Ca²⁺-free conditions to 2.5 mM Ca²⁺. PASMCs were either left untreated under normoxic conditions (N), left untreated under hypoxic conditions (HCON), treated with nontargeted siRNA under hypoxic conditions (HsiNT), or treated with siRNA targeted to STIM1 under hypoxic conditions (HsiSTIM1). A: Representative raw trace illustrating the changes in [Ca²⁺]i (presented as fluorescence intensity (FI) in PASMCs in different groups. B: Summary of the data illustrated in showing averaged changes in fluorescence after 2.5 mM Ca²⁺ restoration. *:P < 0.05 compared with the Control group and #:P < 0.05 compared with the HCON and HsiNT group. The results are expressed as the mean ± SEM of three separate experiments.