Impact of KvLQT1 potassium channel modulation on alveolar fluid homeostasis in an animal model of thiourea-induced lung edema

Abstract

Alveolar ion and fluid absorption is essential for lung homeostasis in healthy conditions as well as for the resorption of lung edema, a key feature of acute respiratory distress syndrome. Liquid absorption is driven by active transepithelial sodium transport, through apical ENaC Na+ channels and basolateral Na+/K+-ATPase. Our previous work unveiled that KvLQT1 K+ channels also participate in the control of Na+/liquid absorption in alveolar epithelial cells. Our aim was to further investigate the function of KvLQT1 channels and their interplay with other channels/transporters involved in ion/liquid transport in vivo using adult wild-type (WT) and KvLQT1 knock-out (KO) mice under physiological conditions and after thiourea-induced lung edema. A slight but significant increase in water lung content (WLC) was observed in naïve KvLQT1-KO mice, relative to WT littermates, whereas lung function was generally preserved and histological structure unaltered. Following thiourea-induced lung edema, KvLQT1-KO did not worsen WLC or lung function. Similarly, lung edema was not aggravated by the administration of a KvLQT1 inhibitor (chromanol). However, KvLQT1 activation (R-L3) significantly reduced WLC in thiourea-challenged WT mice. The benefits of R-L3 were prevented in KO or chromanol-treated WT mice. Furthermore, R-L3 treatment had no effect on thiourea-induced endothelial barrier alteration but restored or enhanced the levels of epithelial alveolar AQP5, Na+/K+-ATPase, and ENaC expressions. Altogether, the results indicate the benefits of KvLQT1 activation in the resolution of lung edema, probably through the observed up-regulation of epithelial alveolar channels/transporters involved in ion/water transport.

Function of KvLQT1 potassium channels in a mouse model of bleomycin-induced acute lung injury

“…The initial breeding pairs (on a C57BL/6J background) were kindly provided by Dr. K. Pfeifer. The mouse colony was then maintained by breeding heterozygous mice (male kcnq1 +/−x female kcnq1 +/−) at the Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM) animal care facility and backcrossing with C57BL/6J wild-type mice (purchased from The Jackson Laboratory) every 10 generations ( Aubin Vega et al, 2023 ). Mice were maintained in a controlled environment with ad libitum access to water and food (2018 Teklad global 18% protein rodent diets, Envigo, United States).…”

“…Mice were maintained in a controlled environment with ad libitum access to water and food (2018 Teklad global 18% protein rodent diets, Envigo, United States). Pups were ear punched at weaning for genotyping by PCR (using G-KOF (5′-CCA GGA GTG GGT GGT TCT AC - 3′), G-KONF (5′-CGC TTC CTC GTG CTT TAC G-3′) and G-KOR (5′-GCC AGC ACT AAA GAT CTT GC-3′) primers (Integrated DNA Technologies, US) amplifying 240- and 370-bp products, for WT and mutant alleles, respectively) and were recognized as WT or KO mice ( Aubin Vega et al, 2023 ). All animal procedures were approved by the Institutional Committee for the Protection of Animals (CIPA) at the CRCHUM, in accordance with the guidelines of the Canadian Council for Animal Care (CCAC).…”

“…Mechanical properties (resistance, elastance, and compliance) of the respiratory system were assessed in live WT and KO mice, challenged or not (i.n. PBS) with bleomycin (Bleo, 3 U/kg) using the flexiVent FX system (SCIREQ, Montreal, QC, Canada), as previously described ( Robichaud et al, 2017 ; Aubin Vega et al, 2023 ). Briefly, mice received an administration of xylazine hydrochloride (12 mg/mL, i. p.) 5 min before being deeply anesthetized with sodium pentobarbital (70 mg/kg, i. p.).…”

“…They were then tracheotomized, cannulated (18-gauge metal cannula with a typical resistance of 0.22 cmH 2 O.s/mL), and connected to a computerized small animal ventilator for mechanical ventilation. Details of flexiVent settings, data acquisition, and measurement maneuvers were as previously described in a previous study ( Aubin Vega et al, 2023 ). Briefly, data acquisition was started after two deep lung inflations to 30 cmH 2 O, to open closed lung areas and standardize lung volumes.…”

“…In resected human lung, Sakuma et al showed that a K ATP channel opener favors fluid absorption across the alveolar epithelium, by a mechanism secondarily mediated by amiloride-sensitive Na + channels ( Sakuma et al, 1998 ). Furthermore, in one of our recent studies ( Aubin Vega et al, 2023 ), we showed that KvLQT1 knockout (KO) in mice was associated with a small but significant increase in water lung content under physiological conditions, compared to wild-type (WT) mice, while both the lung function and histological structures were generally preserved in KvLQT1-KO mice. Our data then showed that pharmacological activation of KvLQT1 in WT mice favors the resolution of thiourea-induced lung edema, suggesting a role for KvLQ1 in fluid clearance ( Aubin Vega et al, 2023 ).…”