Figure 3.

IL-13 dependent ASL meniscus absorption requires active ion transport. (a+b) Differentiated HBE cells were cultured ± IL-13 for 3 days. The HBE cells were then mounted in Ussing chambers and the amiloride sensitive Na⁺ absorption (I_Na) and the forskolin stimulated bumetanide sensitive Cl⁻ secretion (I_Cl) was measured. (a) Representative I_SC tracings of HBE cell cultures ± IL-13. (b) Mean I_Na is decreased and I_Cl is increased by IL-13 in HBE cells. Data shown are mean I_Na and I_Cl ± SEM, n = 4 HBE cell cultures, *p < 0.0001 by unpaired Student’s t-test. (c) Apical volume absorption rate after the addition of 10 µL Ringer’s solution bolus (control) is increased by IL-13, but is unchanged when ion transport is inhibited by 100 µM basolateral ouabain or through the addition of 10 μL of apical isosmotic mannitol solution. Data shown are mean absorption rate ± SEM (µL/cm²/hr), n = 3 tissue donors with 6 experimental replicates per donor, **p = 0.0151, ***p = 0.0453, and ****p = 0.0130 all via unpaired Student’s t-test. Control conditions are represented in black, IL-13 treated conditions are represented in red.