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Guanosine nucleotides activate Na transport in human lung epithelial cells
Author(s) -
Ji HongLong,
Chen Lan,
Shrestha Kedar,
Song WeiFeng,
Gao ZhiQian,
Su XueFeng,
Smith Peter R,
Benos Dale J,
Matalon Sadis
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a553-b
Subject(s) - amiloride , epithelial sodium channel , cyclic nucleotide gated ion channel , patch clamp , chemistry , guanosine , biophysics , microbiology and biotechnology , cyclic guanosine monophosphate , medicine , sodium , nucleotide , biochemistry , cyclic nucleotide , receptor , biology , nitric oxide , gene , organic chemistry
Alveolar fluid clearance is controlled by amiloride‐sensitive and cyclic GMP‐sensitive pathways (Norlin, J Appl Physiol 2001). However, the relationship between these two pathways is not known. To examine the regulation of the amiloride‐sensitive Na channel by cGMP, we studied the response of native Na transport to cGMP in H441 monolayers and single cells using Ussing chamber and patch clamp setups. The short‐circuit Na current (Isc) across H441 monolayers was activated by cGMP in a dose‐dependent manner with an EC 50 of 147μM. To inhibit Cl and K channels, CFTR inh172 and glibenclimide were included on both sides of the monolayer. The cGMP‐activated Isc is not CNG‐associated for its insensitivity to diltiazem. In the presence of 1 mM amiloride, cGMP did not evoke any current. Comparable results were obtained from whole‐cell patched H441 cells. Our RT‐PCR and western blot studies suggest that δ, α, β, and γ ENaC subunits were expressed in H441 cells and human lung tissues at the mRNA and protein levels. Furthermore, cGMP stimulated the activity of δαβγ‐ENaC channels heterologously expressed in oocytes. Our data indicate that δαβγ‐ENaC may be part of the cGMP‐sensitive pathway for lung fluid clearance. Supported by AHA 0635355N, DK 054781, HL 31197, and HL 51173