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Role of superoxide anions in mediating the effect of K‐restriction on ROMK channels and renal K excretion
Author(s) -
Wang WenHui,
Babilonia Elisa,
Lin DaoHong
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.21.6.a1331-c
Subject(s) - chemistry , superoxide , medicine , endocrinology , excretion , mitochondrial ros , biochemistry , reactive oxygen species , biology , enzyme
We investigated the effect of H2O2 on ROMK‐like small conductance K (SK) channels in the CCD and the role of NOX2 in mediating the effect of low K intake on renal K excretion and SK channels. K‐restriction increased superoxide concentrations and decreased SK channel activity. The effect of superoxide anions and related products on SK channels has also been shown by experiments in which application of 100 uM H2O2 inhibited SK channels in the rat CCD. The effect of H2O2 was completely abolished by blocking P38, ERK and protein tyrosine kinase. Deletion of gp91phox significantly attenuated the effect of low K intake on superoxide production, c‐Src expression and tyrosine phosphorylation of ROMK. Patch‐clamp experiments demonstrated that the effect of low K intake on SK channel activity was significantly attenuated in the CCD from gp91phox(−/−) mice and completely abolished by tempol treatment. We also used immunocytochemical staining to examine the ROMK distribution in wt, gp91phox(−/−) and wt mice with tempol treatment in response to K restriction. K‐restriction decreased apical staining of ROMK in wt mice. In contrast, a sharp apical ROMK staining was observed in the tempol‐treated wt or gp91phox(−/−) mice. Metabolic cage study has further shown that urinary K loss is significantly higher in gp91phox(−/−) mice than in wt mice. We conclude that superoxide anions play a key role in suppressing K secretion during K restriction and that NOX2 is involved in mediating the effect of low K intake on renal K secretion and ROMK channel activity.