Smoke inhalation injury is the leading cause of death in firefighters and victims. Inhaled hot air and toxic smoke are the predominant hazards to the respiratory epithelium. We aimed to analyze the effects of thermal stress and smoke aldehyde on the permeability of the airway epithelial barrier. Transepithelial resistance (R_TE) and short-circuit current (I_SC) of mouse tracheal epithelial monolayers were digitized by an Ussing chamber setup. Zonula occludens-1 tight junctions were visualized under confocal microscopy. A cell viability test and fluorescein isothiocyanate-dextran assay were performed. Thermal stress (40 °C) decreased R_TE in a two-phase manner. Meanwhile, thermal stress increased I_SC followed by its decline. Na⁺ depletion, amiloride (an inhibitor for epithelial Na⁺ channels [ENaCs]), ouabain (a blocker for Na⁺/K⁺-ATPase), and CFTRinh-172 (a blocker of cystic fibrosis transmembrane regulator [CFTR]) altered the responses of R_TE and I_SC to thermal stress. Steady-state 40 °C increased activity of ENaCs, Na⁺/K⁺-ATPase, and CFTR. Acrolein, one of the main oxidative unsaturated aldehydes in fire smoke, eliminated R_TE and I_SC. Na⁺ depletion, amiloride, ouabain, and CFTRinh-172 suppressed acrolein-sensitive I_SC, but showed activating effects on acrolein-sensitive R_TE. Thermal stress or acrolein disrupted zonula occludens-1 tight junctions, increased fluorescein isothiocyanate-dextran permeability but did not cause cell death or detachment. The synergistic effects of thermal stress and acrolein exacerbated the damage to monolayers. In conclusion, the paracellular pathway mediated by the tight junctions and the transcellular pathway mediated by active and passive ion transport pathways contribute to impairment of the airway epithelial barrier caused by thermal stress and acrolein.

Thermal stress and acrolein are two essential determinants for smoke inhalation injury, impairing airway epithelial barrier.

Transcellular ion transport pathways via the ENaC, CFTR, and Na/K-ATPase are interrupted by both thermal stress and acrolein, one of the most potent smoke toxins.

Heat and acrolein damage the integrity of the airway epithelium through suppressing and relocating the tight junctions.

烟雾吸入伤害是消防员和受害者死亡的主要原因。吸入的热空气和有毒烟雾是呼吸道上皮的主要危害。我们旨在分析热应力和烟醛对气道上皮屏障通透性的影响。小鼠气管上皮单层的跨上皮电阻 ( R _TE ) 和短路电流 ( I _SC ) 由 Ussing 室设置数字化。Zonula occludens-1 紧密连接在共聚焦显微镜下可视化。进行细胞活力测试和荧光素异硫氰酸酯-葡聚糖测定。热应力 (40 °C)以两相方式降低了R _TE。同时，热应力增加了I_SC随后下降。Na ⁺消耗、阿米洛利（上皮 Na ⁺通道 [ENaCs]的抑制剂）、哇巴因（Na ⁺ /K ⁺ -ATP 酶的阻滞剂）和 CFTRinh-172（囊性纤维化跨膜调节剂 [CFTR] 的阻滞剂）改变了R _TE和I _SC对热应力的响应。稳态 40 °C 增加了 ENaCs、Na ⁺ /K ⁺ -ATPase 和 CFTR 的活性。丙烯醛是火灾烟雾中主要的氧化性不饱和醛之一，可消除R _TE和I _SC。钠⁺耗竭、阿米洛利、哇巴因和 CFTRinh-172 抑制了丙烯醛敏感的I _SC，但对丙烯醛敏感的R _TE显示出激活作用。热应力或丙烯醛破坏了封闭带-1 的紧密连接，增加了异硫氰酸荧光素-葡聚糖的渗透性，但不会导致细胞死亡或脱离。热应力和丙烯醛的协同作用加剧了对单层的损伤。总之，由紧密连接介导的细胞旁通路和由主动和被动离子转运通路介导的跨细胞通路有助于由热应力和丙烯醛引起的气道上皮屏障受损。

热应激和丙烯醛是烟雾吸入损伤的两个重要决定因素，损害气道上皮屏障。

通过 ENaC、CFTR 和 Na/K-ATPase 的跨细胞离子转运途径被热应激和丙烯醛（最有效的烟雾毒素之一）中断。

热量和丙烯醛通过抑制和重新定位紧密连接来破坏气道上皮的完整性。