Figure 2.

A: Representative I_SC tracing of human sinonasal epithelial (HSNE) cultures. HSNE cells grown on transwell permeable supports and incubated in 1% O₂ or physiologic O₂ (control, 21%) were mounted in modified Ussing chambers under short-circuit conditions and sequentially exposed to amiloride (100µM); forskolin (20 µM); INH-172 (10 µM) and uridine triphosphate (UTP) (150 µM). Note the relative increase in ΔI_SC attributable to sodium blockade with amiloride (negative deflection) and decrease in forskolin-stimulated ΔI_SC at 24 hours under hypoxic conditions.

B. Change in short-circuit current (ΔI_SC) in human sinonasal epithelial cultures after 12 and 24 hours under hypoxic (1% O₂) conditions and following 24 hour recovery period under physiologic conditions (21% O₂). Forskolin-stimulated ΔI_SC was sensitive to hypoxic stress, and demonstrated significant reduction in CFTR-mediated Cl⁻ transport (n ≥ 6 per condition). Decreased ΔI_SC from INH-172 blockade verified the contribution of CFTR to the I_SC. Conversely, CaCC-mediated ΔI_SC (UTP-stimulated) was more susceptible to oxygen restriction compared to MNSE and demonstrated early inhibition at 12 hours. Sodium absorption (amiloride blockade) was significantly increased at 12 hours and returned back to baseline by 24 hours. HSNE demonstrated significant recovery of Cl⁻ transport following 24 hours in a physiologic O₂ (21%) environment.