Superoxide anions are involved in mediating the effect of low K intake on c-Src expression and renal K secretion in the cortical collecting duct.
We previously demonstrated that low K intake stimulated the expression of c-Src and that stimulation of protein tyrosine kinase inhibited ROMK channel activity (Wei, Y., Bloom, P., Lin, D. H., Gu, R. M., and Wang, W. H. (2001) Am. J. Physiol. 281, F206-F212). Decreases in dietary K content significantly increased O(2)(-) levels and the phosphorylation of c-Jun, a transcription factor, in renal cortex and outer medulla. The role of O(2)(-) and related products such as H(2)O(2) in stimulating the expression of protein tyrosine kinase is suggested by the observation that addition of 50-200 microm H(2)O(2) increased the phosphorylation of c-Jun and the expression of c-Src in M1 cells, a mouse collecting duct principal cell line. The effect of H(2)O(2) on c-Src expression was completely abolished with cyclohexamide or actinomycin D. The treatment of animals on a K-deficient (KD) diet with tempol for 7 days significantly decreased the production of O(2)(-), c-Jun phosphorylation, and c-Src expression. Moreover, low K intake decreased the activity of ROMK-like small conductance channels from 1.37 (control K diet) to 0.5 in the cortical collecting duct and increased the tyrosine phosphorylation of ROMK in the renal cortex and outer medulla. In contrast, the tempol treatment not only increased channel activity to 1.1 in the cortical collecting duct but also decreased the tyrosine phosphorylation of ROMK from rats on a KD diet. Finally, suppressing O(2)(-) production with tempol significantly increased renal K excretion measured with metabolic cage and lowered the plasma K concentration in comparison with those on a KD diet alone without tempol. We conclude that O(2)(-) and related products play a role in mediating the effect of low K intake on c-Src expression and in suppressing ROMK channel activity and renal K secretion.
Babilonia
Elisa
E
Department of Pharmacology, New York Medical College, Valhalla, New York 10595, USA.
Wei
Yuan
Y
Sterling
Hyacinth
H
Kaminski
Pawel
P
Wolin
Michael
M
Wang
Wen-Hui
WH
D000818:Animals; D015153:Blotting, Western; D000081247:CSK Tyrosine-Protein Kinase; D002460:Cell Line; D003497:Cyclic N-Oxides / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005609:Free Radicals; D006861:Hydrogen Peroxide / Q000494:pharmacology; D047468:Immunoprecipitation; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D007668:Kidney / Q000378:metabolism*; D007672:Kidney Cortex / Q000378:metabolism; D007685:Kidney Tubules, Collecting / Q000166:cytology; D051379:Mice; D010100:Oxygen / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D011188:Potassium / Q000737:chemistry*; D011485:Protein Binding; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species; D013113:Spin Labels; D013481:Superoxides / Q000737:chemistry; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases
D003497:Cyclic N-Oxides; D005609:Free Radicals; D011500:Protein Synthesis Inhibitors; D017382:Reactive Oxygen Species; D013113:Spin Labels; D013481:Superoxides; D003609:Dactinomycin; D014443:Tyrosine; D003513:Cycloheximide; D006861:Hydrogen Peroxide; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D011188:Potassium; D010100:Oxygen; C001803:tempol