Figure 3.

Effect of CFTR inhibitors on intracellular sphingolipid levels in lung endothelial cells. (A–C) Ceramide, S1P, and dihydroceramide levels were measured by tandem mass spectrometry in primary human lung microvascular endothelial cells treated with H₂O₂ (250 μM, 6 h) in the presence of the CFTR inhibitor CFTR_inh-172 (20 μM). Sphingolipid levels were normalized by intracellular phospholipids (inorganic phosphorus content, Pi) and plotted as mean ± SEM (n = 3; *P < 0.05 versus control; ^#P < 0.05 versus H₂O₂). (D) The ratio of ceramide/S1P in lung endothelial cells, an indicator of pro-apoptotic/anti-apoptotic intracellular balance, was calculated from the values measured in A and B (mean ± SEM; n = 3; *P < 0.05 versus control; ^#P < 0.05 versus H₂O₂ treatment).