Fig. 1.

Thermal stress alternates bioelectric features in mouse tracheal epithelial (MTE) and human bronchial epithelial (HBE) monolayers. (a) Representative transepithelial resistance (R_TE) trace in MTE monolayer mounted on an Ussing chamber setup. R_TE was decreased in a two-phase manner (P1 and P2 were labeled) during the temperature of the bath solution was raised to 40°C (red line) from 37°C (black line). When the temperature rose to 38.5°C, the changes in R_TE and I_SC were observed, and it took 4.7 min for the course from 37°C to 40°C. (b) Short-circuit current (I_SC) trace recorded simultaneously in the same MTE monolayer. P1 and P2 of I_SC were defined using the R_TE time course. I_SC was increased at P1 and decreased at P2. (c) Average R_TE levels of MTE monolayers at different time points during thermal stress. Student’s t-test. ***P < 0.001. n = 20. (d) Average I_SC levels of MTE monolayers. Student’s t-test. ***P < 0.001. n = 20. (e) Time for reducing half of the total R_TE (τ_1/2). The τ_1/2 value was computed by fitting R_TE raw data with the ExpDec1 function. (y₀ = 0.36 ± 0.04, A = 0.87 ± 0.04 [P1]; y₀ = −0.87 ± 0.11, A = 3.22 ± 0.36 [P2]). Student’s t-test. ***P < 0.001. n = 12. (f) Representative R_TE trace in HBE monolayer. R_TE was decreased during the temperature of the bath solution was elevated to 40°C (red line) from 37°C (black line). (g) I_SC trace recorded simultaneously in the same HBE monolayer. I_SC was increased to a high and stable level during thermal stress. (h) Average R_TE levels of HBE monolayers under the conditions of 37°C and 40°C. Student’s t-test. NS, no significance. n = 6. (i) Average I_SC levels of HBE monolayers. Student’s t-test. *P < 0.05. n = 6.