Fig. 2

Acidic pH or TNF-α-stimulated CXCL8 secretion in ASMCs a The absolute values of CXCL8 secreted at pH 6.3 and 7.4 in the lot of ASMCs mainly used in this study are shown. In all independent experiments, extracellular pH 6.3 increases CXCL8 secretion at 24 h in ASMCs compared with pH 7.4 (n = 11, **; P < 0.01). b Extracellular acidification (pH 6.3) induces significant increase of CXCL8 secretion at 24 h compared with pH 7.4 in other three kinds of ASMCs, lot A, B and C, originated from different non-diseased individuals (mean ± SEM, n = 4; **, P < 0.01; *, P < 0.05). c The amount of CXCL8 generated from ASMCs at 24 h after pH 6.3-stimulation is 23.5% of that generated from TNF-α (10 ng/mL)-stimulated ASMCs. Data are expressed as percentages of CXCL8 values obtained at pH 7.4 without TNF-α for 24 h (mean ± SEM, n = 4; **, P < 0.01; *, P < 0.05)