Nasal potential difference in βENaC-overexpressing mouse reveals pH-sensitive channel hyperactivity and shift of subunits stoichiometry
(2017) 40th European Cystic Fibrosis Conference — Location: Sevilla, Spain (7.June.2017)
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- Objectives: To characterize transepithelial nasal potential difference in β- ENaC overexpressing mouse model engineered to mimic CF airway disease. Methods: We used transepithelial potential difference (PD) to measure ion transport across the nasal mucosa of wild-type and scnn1b-Tg heterozygous (Tg/ + ) mice. The following parameters were recorded: (1) the most negative basal PD value; (2) change in PD after nasal perfusion with buffered Ringer’s solution at pH 7.4 but no change with pH 6.5; (3) decrease in PD after perfusion with Ringer’s solution containing 10−4 M amiloride; (4) subsequent changes in PD after perfusion with Ringer’s solution in which Cl− was replaced by gluconate, and amiloride and 10−5 M forskolin were added. To test the hypothesis that elevated Na + transport in Tg/ + mouse airways is due to an increased number of αβγENaC channels or a possible change in subunits stoichiometry, we analyzed ENaC subunit transcripts in mouse nasal epithelium and in nasal epithelial cells in 3D primary cultures. Results: More polarized basal PD values were recorded in Tg/ + than in wild-type mice. In Tg/+, but not in wild-type, perfusion of Ringer’s-pH 7.4 rapidly induced a small depolarization (+4mV) that was prevented by adjusting the pH to 6.5. The response to amiloride was significantly increased (+50%) in Tg/+ compared to wild-type mice. Perfusion of chloride-free containing forskolin induced a hyperpolarization of similar magnitude in Tg/+ and in wild-type mice. Both α and βENaC transcript levels were elevated in nasal cells derived from Tg/+ mice with no significant change in γ-subunit expression. Conclusion: Our data indicate that the CFTR-dependent chloride conductance is not affected by ENaC hyperactivity in mice. We showed here a pHsensitive hyperactivity of ENaC in nasal epithelium of scnn1b-Tg mice possibly associated with a switch in subunit stoichiometry of the ENaC channel. However, the possible role of inflammation should also be considered.
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Leal, T., Beka, M., Panin, N., Mall, M. A., & Noël, S. (2017). Nasal potential difference in βENaC-overexpressing mouse reveals pH-sensitive channel hyperactivity and shift of subunits stoichiometry. Journal of Cystic Fibrosis, 16(S1), S72. https://hdl.handle.net/2078.5/176151 (Original work published 2017)