title: Impairment of Na/K-ATPase signaling in renal proximal tubule contributes to Dahl salt-sensitive hypertension.
abstract: We have observed that, in renal proximal tubular cells, cardiotonic steroids such as ouabain in vitro signal through Na/K-ATPase, which results in inhibition of transepithelial (22)Na(+) transport by redistributing Na/K-ATPase and NHE3. In the present study, we investigate the role of Na/K-ATPase signaling in renal sodium excretion and blood pressure regulation in vivo. In Sprague-Dawley rats, high salt diet activated c-Src and induced redistribution of Na/K-ATPase and NHE3 in renal proximal tubules. In Dahl salt sensitive (S) and resistant (R) rats given high dietary salt, we found different effects on blood pressure but, more interestingly, different effects on renal salt handling. These differences could be explained by different signaling through the proximal tubular Na/K-ATPase. Specifically, in Dahl R rats, high salt diet significantly stimulated phosphorylation of c-Src and ERK1/2, reduced Na/K-ATPase activity and NHE3 activity, and caused redistribution of Na/K-ATPase and NHE3. In contrast, these adaptations were either much less effective or not seen in the Dahl S rats. We also studied the primary culture of renal proximal tubule isolated from Dahl S and R rats fed a low salt diet. In this system, ouabain induced Na/K-ATPase/c-Src signaling and redistribution of Na/K-ATPase and NHE3 in the Dahl R rats, but not in the Dahl S rats. Our data suggested that impairment of Na/K-ATPase signaling and consequent regulation of Na/K-ATPase and NHE3 in renal proximal tubule may contribute to salt-induced hypertension in the Dahl S rat.
authors.affiliation: Department of Medicine, University of Toledo College of Medicine, Toledo, Ohio 43614, USA. Jiang.Liu@utoledo.edu
authors.forename: Jiang
authors.initials: J
authors.lastname: Liu
authors.forename: Yanling
authors.initials: Y
authors.lastname: Yan
authors.forename: Lijun
authors.initials: L
authors.lastname: Liu
authors.forename: Zijian
authors.initials: Z
authors.lastname: Xie
authors.forename: Deepak
authors.initials: D
authors.lastname: Malhotra
authors.forename: Bina
authors.initials: B
authors.lastname: Joe
authors.forename: Joseph I
authors.initials: JI
authors.lastname: Shapiro
mesh_terms: D000818:Animals; D000081247:CSK Tyrosine-Protein Kinase; D006973:Hypertension / Q000139:chemically induced / Q000201:enzymology* / Q000235:genetics; D007687:Kidney Tubules, Proximal / Q000201:enzymology*; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects / Q000235:genetics; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D051381:Rats; D020303:Rats, Inbred Dahl; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D017673:Sodium Chloride, Dietary / Q000009:adverse effects / Q000494:pharmacology; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics / Q000378:metabolism*; D019061:src-Family Kinases
chemical_list: C000613387:Slc9a3 protein, rat; D017673:Sodium Chloride, Dietary; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; D048052:Mitogen-Activated Protein Kinase 3; D000254:Sodium-Potassium-Exchanging ATPase