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Editorial
. 2024 Sep 15;210(6):705-707.
doi: 10.1164/rccm.202404-0727ED.

Pulmonary Ionocytes: What Are They Transporting and Which Way?

Kenichi Okuda  1   2 , Martina Gentzsch  1   3
Affiliations
Editorial

Pulmonary Ionocytes: What Are They Transporting and Which Way?

Kenichi Okuda et al. Am J Respir Crit Care Med. .
No abstract available

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Figures

Figure 1.
Figure 1.
Models proposed for pulmonary ionocyte and club cell functions. (A) Ionocytes participate in Cl−/fluid secretion, facilitated by cystic fibrosis transmembrane conductance regulator (CFTR)- and NKCC1-mediated ion transport processes (12). (B) Ionocytes mediate Cl−/fluid absorption, a process involving ion movement facilitated by CFTR, epithelial sodium channel (ENaC), and barttin/Cl− channels (13). (C) Ionocytes control the airway surface liquid pH through a Cl−/HCO3− exchange mechanism (14). CFTR contributes indirectly to HCO3− movement in ionocytes, which is mediated by anion exchanger protein 2. (D) Cl−/fluid secretion in club cells as described by Luan and colleagues (14). (E) Regulated Cl−/fluid secretion under physiological conditions. Mechanical stretch associated with normal tidal breathing promotes ATP release from airway epithelia, which activates P2Y2 signaling that inhibits ENaC and promotes CFTR-mediated Cl− secretion in club cells that is associated with paracellular Na+ movement (8). (F) In a nonregulated state (i.e., when the ATP concentration is low as a result of increased airway surface liquid volume), ENaC is active and club cells absorb Na+/fluid, which is accompanied by paracellular Cl− movement. Created with BioRender.com. AE2 = anion exchanger 2, Cl−HCO3− exchanger; NaK pump = Na+/K+ ATPase; NHE2 = Na+/H+ exchanger 2; NKCC1 = Na+-K+-2Cl− cotransporter 1.
See this image and copyright information in PMC

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References

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