FIGURE 5.

Effect of Orai1 small interference RNA (siRNA) on intracellular Ca²⁺ ([Ca²⁺]_i) and store-operated Ca²⁺ entry (SOCE) in human airway smooth muscle (ASM) cells. a) Transfection efficiency of Orai1 using siRNA was verified by Western blot analysis. Smooth muscle α-actin served as loading control. b) Orai1 siRNA significantly reduced histamine-induced [Ca²⁺]_i responses compared with vehicle and negative control. c) Orai1 siRNA significantly reduced SOCE compared with vehicle control. Exposure to 5 µM Cav-1-specific caveolin scaffolding domain peptide (CSD; 6 h) significantly reduced SOCE (confirming the Cav-1 siRNA effect on SOCE in figure 3). Combination of Orai1 siRNA and CSD also significantly reduced SOCE compared with vehicle control but not in comparison with Orai1 siRNA or CSD alone. Cav-1-mRed significantly increased SOCE, which was decreased by Orai1 siRNA. Orai1 siRNA significantly reduced SOCE in the presence and absence of tumour necrosis factor (TNF)-α, confirming the importance of Orai1 during airway inflammation. Data are presented as mean±se. ^*: significant Orai1 siRNA effect; ^#: significant CSD effect; ^¶: significant Cav-1-mRed effect; ^§: significant TNF-α effect (all p<0.05).