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Aldosterone regulated superoxide (O 2 − ) production increases amiloride‐sensitive epithelial sodium channel (ENaC) activity in A6 distal kidney cells
Author(s) -
Self Julie L.,
Helms My N.,
Eaton Douglas C.
Publication year - 2006
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.20.4.a796-b
Subject(s) - epithelial sodium channel , aldosterone , amiloride , medicine , endocrinology , chemistry , superoxide , kidney , nadph oxidase , mineralocorticoid , sodium , biology , biochemistry , reactive oxygen species , enzyme , organic chemistry
The molecular mechanisms behind aldosterone‐mediated regulation of ENaC activity in the kidneys are not clearly understood. Our current study suggests that O 2 − production by aldosterone may play an important role in the signal transduction pathway leading to ENaC activity. Methods A6 distal kidney cells were grown on permeable supports and aldosterone regulation of O 2 − production was assayed using dihydroethidium labeling, which increases its fluorescence in the presence of O 2 − . Short circuit current (I SC ) values, which reflect Na channel activity, were measured using an epithelial voltohmeter (World Precision Instruments). Results 1.5μM aldosterone significantly increased O 2 − production compared to serum/hormone restricted A6 cells. Sequestering O 2 − with TEMPO decreased I SC values from 7.58 ± 0.34μA/cm 2 to 6.27 ± 0.38μA/cm 2 (P<0.05) within 5 min and continued to depress I SC for 2 hours. Conversely, hypoxanthine and xanthine oxidase release of O 2 − increased I SC values from 9.31 ± 0.66μA/cm 2 to 13.98 ± 1.14μA/cm 2 (P< 0.005) after 30 min. Conclusion Aldosterone regulation of superoxide production may play an important role in controlling ENaC activity in renal cells.