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Apocynin but not TEMPOL decreases Na+,K+‐ATPase α1 subunit expression in opossum kidney cells
Author(s) -
Silva Elisabete Ferreira,
SoaresdaSilva Patricio
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.a438-a
Subject(s) - apocynin , western blot , chemistry , superoxide dismutase , nadph oxidase , extracellular , microbiology and biotechnology , superoxide , oxidative stress , endocrinology , biology , biochemistry , enzyme , gene
The present study examined the effects of a NADPH oxidase inhibitor (apocynin) and a superoxide dismutase mimetic (TEMPOL) in the regulation of Na+,K+‐ATPase (NKA) in opossum kidney (OK) cells. Hydrogen peroxide levels were determined with a fluorescent assay. Expression of NKA subunits was determined by western blotting and in cell western. In aged OK cells, increases in NKA activity were accompanied by increases in hydrogen peroxide production and accumulation in the extracellular medium. Apocynine (300 μM), but not TEMPOL (300 μM), treatment during 4 days induced a 48.3±0.8 % decrease in hydrogen peroxide accumulation in extracellular medium. Under these conditions apocynin treatment was accompanied by a decrease in NKA activity (25.9±6.7 % reduction). This was paralleled by a 35.7±7.6 % and a 25.6±3.6 % decrease in α1 subunit NKA expression determined by western blot and in cell western, respectively. Treatment with TEMPOL did not alter α1 subunit NKA expression when determined by western blot; however, a 21.1±5.1 % increase in α1 subunit NKA expression was observed while using in cell western measurements. It is concluded that oxidative stress plays a role in the long‐term regulation of NKA activity. The results suggest that increased levels of hydrogen peroxide may account for the increased NKA activity in aged cells. Supported by grant POCI/SAU‐FCF/59207/2004