Inhibition of amiloride-sensitive sodium-channel activity in distal lung epithelial cells by nitric oxide

• Published in: American journal of physiology. Lung cellular and molecular physiology Vol. 274; no. 3; pp. 378 - L387
• Main Authors: Ding, Jin Wen, Dickie, John, O'Brodovich, Hugh, Shintani, Yutaka, Rafii, Bijan, Hackam, David, Marunaka, Yoshinori, Rotstein, Ori D
• Format: Journal Article
• Language: English
• Published: United States 01.03.1998
• Subjects: Amiloride - pharmacology; Animals; Coculture Techniques; Culture Techniques; Enzyme Induction; Epithelial Cells - drug effects; Epithelial Cells - metabolism; Lipopolysaccharides - pharmacology; Lung - cytology; Lung - drug effects; Lung - metabolism; Macrophages - drug effects; Macrophages - metabolism; Male; Nitric Oxide - pharmacology; Nitric Oxide Synthase - biosynthesis; Nitric Oxide Synthase - metabolism; Nitric Oxide Synthase Type II; Penicillamine - analogs & derivatives; Penicillamine - pharmacology; Rats; Rats, Wistar; RNA, Messenger - metabolism; S-Nitroso-N-Acetylpenicillamine; Sodium Channel Blockers; Sodium Channels - drug effects; Sodium Channels - metabolism
• ISSN: 1040-0605; 0002-9513; 1522-1504
• DOI: 10.1152/ajplung.1998.274.3.L378

1  Department of Surgery and Medical Research Council of Canada Group in Mechanisms of Organ Injury, Toronto Hospital, University of Toronto, and Toronto Hospital Research Institute, Toronto M5G 2C4; and 2  Medical Research Council of Canada Group in Lung Development and Department of Pediatrics (Respiratory Research), University of Toronto and The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8 Distal lung epithelial cells (DLECs) play an active role in fluid clearance from the alveolus by virtue of their ability to actively transport Na + from the alveolus to the interstitial space. The present study evaluated the ability of activated macrophages to modulate the bioelectric properties of DLECs. Low numbers of lipopolysaccharide (LPS)-treated macrophages were able to significantly reduce amiloride-sensitive short-circuit current ( I sc ) without affecting total I sc or monolayer resistance. This was associated with a rise in the flufenamic acid-sensitive component of the I sc . The effect was reversed by the addition of N -monomethyl- L -arginine to the medium, implying a role for nitric oxide. We hypothesized that macrophages exerted their effect by expressing inducible nitric oxide synthase (iNOS) in DLECs. The products of LPS-treated macrophages increased the levels of iNOS protein and mRNA transcripts in DLECs as well as causing a rise in iNOS activity. Immunofluorescence microscopy of LPS-stimulated macrophage-DLEC cocultures with anti-nitrotyrosine antibodies provided evidence for the generation of peroxynitrite in macrophages but not in DLECs. These data indicate that activated macrophages in the lung may contribute to impaired resolution of acute respiratory distress syndrome and suggest a novel mechanism whereby nitric oxide might alter cell function by altering its ion-transporting phenotype. distal lung epithelium; macrophages; lung injury