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Activated Neutrophils and Na Transport in A549 Cells
Author(s) -
Kapur Arvinder K,
Carlton David P
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.a549-d
Subject(s) - amiloride , chemistry , superoxide dismutase , a549 cell , incubation , catalase , andrology , lung , microbiology and biotechnology , medicine , endocrinology , biochemistry , sodium , cell , oxidative stress , biology , organic chemistry
Neutrophils accumulate in the distal airspace in a variety of lung injury syndromes. To see if neutrophils might affect function of the distal respiratory epithelium, we studied Na transport in A549 cells in response to an 8h co‐incubation with neutrophils (PMN) isolated from blood and activated by phorbol myristate acetate (10 ng/mL). To assess Na transport, we measured 22 Na accumulation over 5 min in the presence and absence of amiloride (10 −4 M). Activated neutrophils (5 million/well) had no effect on A549 cell number (control: 1.7 x 10 6 ± 0.3 vs PMN‐exposed: 1.8 x 10 6 ± 0.4 cells/well, n=6, mean ± SD), or on viability measured by vital dye exclusion (control: 98 ± 2% vs PMN‐exposed: 97 ± 4%, n=6), but they decreased amiloride‐sensitive Na uptake on average by 30% (control: 51 ± 18 vs. PMN‐exposed: 34 ± 13 nmol/5 min/mg protein, n=6, p < 0.05). To see if oxidants might play a role in mediating this effect, we treated A549 cells with superoxide dismutase (300 U/mL) and catalase (4 mg/mL) and found that the antioxidants blunted the decrease in Na uptake caused by activated neutrophils by nearly 70% (control: 19 ± 3 vs PMN‐exposed: 8 ± 2 vs antioxidants: 16 ± 4 nmol/5 min/mg protein, n=6). Thus, activated neutrophils decrease Na uptake in A549 cells, and this effect is diminished by antioxidants. We speculate that activated neutrophils in the distal lung may impair Na‐linked fluid clearance from the airspace and promote lung edema.