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

Abstract

Summary 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.

Durable Changes to Airway Mucus and Fluid Secretion Following Cholinergic Challenge

“…We measured the apical surface fluid meniscus using previously published methods [19,30]. Baseline volumes were consistent with previously published values ( Figure 3A) [19,30]. In saline-treated cultures, basolateral carbachol induced a significant increase in fluid secretion that was detected 30 minutes post-stimulation ( Figure 3A, 3B).…”

“…Thus, we examined known modulators of mucus biophysical properties, namely fluid and ion transport, in primary cultures of porcine airway epithelia treated with bethanechol or saline control. We measured the apical surface fluid meniscus using previously published methods [19,30]. Baseline volumes were consistent with previously published values ( Figure 3A) [19,30].…”

“…Medicine and Science, North Chicago, Illinois, USA); and 4,4'-Diisothiocyano-2,2'stilbenedisulfonic acid (DIDS) disodium salt (Sigma) [19].…”

“…Cultured epithelia were studied in modified Ussing chambers (EasyMount Ussing Chamber System; Physiologic Instruments) as previously reported [19]. Transepithelial voltage was maintained at 0 mV and short-circuit current (Isc) measured (VCC MC-8; Physiologic Instruments).…”

Bone structural, biomechanical, and histomorphometric characteristics of the hindlimb skeleton in the marsh rice rat (Oryzomys palustris)

“…Indeed, the rice rat has been used to study photoperiod and the pineal gland's role in reproduction and reproductive development (Edmonds et al, 2005, 1995; Edmonds & Stetson, 1993, 1994, 2001). They have also been utilized for studying the airway epithelium and disclose the distinctive transport properties that these species possess in their airways, which may explain their ability to survive in marsh salt environments (Kuan et al, 2019). The rice rat is also a unique species for studying retinal pigmented epithelium degeneration (Casavant et al, 2000; Fukuda et al, 2021; Grahn et al, 2005).…”