Fig. 5.

Airway surface liquid pH in ATP12A-overexpressing cells. ASL pH measurements were performed using a microsensor pH electrode in thin-film, unperturbed ASL. Two independent cell models (a, b) primary human airway epithelial cells and (c, d) Calu-3 cells were transfected to overexpress ATP12A or empty vector (control cells). a In primary human airway epithelial cells with serosal 30 mM HCO3⁻, ASL pH was increased by ~0.31 pH units in ATP12A-overexpressing cells compared to vector controls (n = 3; p < 0.01). Hence, in the presence of serosal HCO3⁻, overexpressing of ATP12A did not result in ASL acidification. b In primary human airway epithelial cells with serosal 20 mM HEPES, ASL pH of ATP12A-overexpressing cells was markedly reduced (~0.88 pH units) compared to vector controls (n = 3; p < 0.01). c In Calu-3 cells with serosal 30 mM HCO3⁻, ASL pH was slightly reduced (~0.06 pH units) in ATP12A-overexpressing cells compared to vector controls (n = 3; p = 0.04). d In Calu-3 cells with serosal 20 mM HEPES, ASL pH was markedly reduced (~1.11 pH units) in ATP12A-overexpressing Calu-3 cells compared to vector control cells (n = 3; p < 0.01). All statistical analyses were performed using unpaired t-tests. Data represented as mean ± s.d.; *p < 0.05; **p < 0.01; ***p < 0.001