Role of gp91phox -containing NADPH oxidase in mediating the effect of K restriction on ROMK channels and renal K excretion.
Previous study has demonstrated that superoxide and the related products are involved in mediating the effect of low K intake on renal K secretion and ROMK channel activity in the cortical collecting duct (CCD). This study investigated the role of gp91(phox)-containing NADPH oxidase (NOXII) in mediating the effect of low K intake on renal K excretion and ROMK channel activity in gp91(-/-) mice. K depletion increased superoxide levels, phosphorylation of c-Jun, expression of c-Src, and tyrosine phosphorylation of ROMK in renal cortex and outer medulla in wild-type (WT) mice. In contrast, tempol treatment in WT mice abolished whereas deletion of gp91 significantly attenuated the effect of low K intake on superoxide production, c-Jun phosphorylation, c-Src expression, and tyrosine phosphorylation of ROMK. Patch-clamp experiments demonstrated that low K intake decreased mean product of channel number (N) and open probability (P) (NP(o)) of ROMK channels from 1.1 to 0.4 in the CCD. However, the effect of low K intake on ROMK channel activity was significantly attenuated in the CCD from gp91(-/-) mice and completely abolished by tempol treatment. Immunocytochemical staining also was used to examine the ROMK distribution in WT, gp91(-/-), 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 gp91(-/-) mice. Metabolic cage study further showed that urinary K loss is significantly higher in gp91(-/-) mice than in WT mice. It is concluded that superoxide anions play a key role in suppressing K secretion during K restriction and that NOXII is involved in mediating the effect of low K intake on renal K secretion and ROMK channel activity.
Babilonia
Elisa
E
Department of Pharmacology, New York Medical College, Valhalla, NY 10595, USA.
Lin
Daohong
D
Zhang
Yan
Y
Wei
Yuan
Y
Yue
Peng
P
Wang
Wen-Hui
WH
D000818:Animals; D007668:Kidney / Q000378:metabolism*; D008297:Male; D008562:Membrane Glycoproteins / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000502:physiology*; D011188:Potassium / Q000378:metabolism* / Q000652:urine; D024661:Potassium Channels, Inwardly Rectifying / Q000502:physiology*
C086989:KCNJ1 protein, human; D008562:Membrane Glycoproteins; D024661:Potassium Channels, Inwardly Rectifying; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D011188:Potassium