Attenuated Amiloride-Sensitive Current and Augmented Calcium-Activated Chloride Current in Marsh Rice Rat (Oryzomys palustris) Airways

• Published in: iScience 2019-09, Vol.19, p.737-748
• Main Authors: Kuan, Shin-Ping, Liao, Yan-Shin J., Davis, Katelyn M., Messer, Jonathan G., Zubcevic, Jasenka, Aguirre, J. Ignacio, Reznikov, Leah R.
• Format: Article
• Language: English
• Subjects: Bio-Electrochemistry: Physiology; Molecular Physiology
• ISSN: 2589-0042; 2589-0042
• DOI: 10.1016/j.isci.2019.08.011

Prolonged heat and sea salt aerosols pose a challenge for the mammalian airway, placing the protective airway surface liquid (ASL) at risk for desiccation. Thus, mammals inhabiting salt marshes might have acquired adaptations for ASL regulation. We studied the airways of the rice rat, a rodent that inhabits salt marshes. We discovered negligible Na+ transport through the epithelial sodium channel (ENaC). In contrast, carbachol induced a large Cl− secretory current that was blocked by the calcium-activated chloride channel (CaCC) inhibitor CaCCinhi-A01. Decreased mRNA expression of α, β, and γ ENaC, and increased mRNA expression of the CaCC transmembrane member 16A, distinguished the rice rat airway. Rice rat airway cultures also secreted fluid in response to carbachol and displayed an exaggerated expansion of the ASL volume when challenged with 3.5% NaCl. These data suggest that the rice rat airway might possess unique ion transport adaptations to facilitate survival in the salt marsh environment. [Display omitted] •Rice rat airway cultures show limited epithelial sodium channel activity•mRNA expression levels of epithelial sodium channel were decreased•Exaggerated calcium-activated chloride channel activity was also observed•Rice rat airway fluid secretion properties were unique compared to other mammals Bio-Electrochemistry: Physiology; Molecular Physiology