Figure 8. Hypercapnia reduces the volume of forskolin‐stimulated fluid secretion in Calu‐3 cells .

Cells were stimulated with forskolin (Fsk; 5 μm) and incubated for 24 h in either 5% CO₂ (v/v) in air or 10% CO₂ (v/v) in air in high Cl⁻ Krebs solution at 37°C. A, the effect of chronic hypercapnia on the volume of fluid secreted over 24 h. **Significant effect of forskolin stimulation compared to unstimulated control cells (P < 0.01; ***P < 0.001); †significant effect of 10% CO₂ (P < 0.05). Data represent mean ± SEM; n = 3 for each. B, the increase in pH of forskolin‐stimulated secreted fluid relative to unstimulated control cells. Data represent mean ± SEM; n = 3 for each. C, the effects of forskolin and hypercapnia on the amount of glycoprotein present in the secreted fluid, quantified by the PAS assay. Data represent mean ± SEM; n = 3 for each.