title: HV1 acts as a sodium sensor and promotes superoxide production in medullary thick ascending limb of Dahl salt-sensitive rats.
abstract: We previously characterized a H(+) transport pathway in medullary thick ascending limb nephron segments that when activated stimulated the production of superoxide by nicotinamide adenine dinucleotide phosphate oxidase. Importantly, the activity of this pathway was greater in Dahl salt-sensitive rats than salt-resistant (SS.13(BN)) rats, and superoxide production was enhanced in low Na(+) media. The goal of this study was to determine the molecular identity of this pathway and its relationship to Na(+). We hypothesized that the voltage-gated proton channel, HV1, was the source of superoxide-stimulating H(+) currents. To test this hypothesis, we developed HV1(-/-) null mutant rats on the Dahl salt-sensitive rat genetic background using zinc-finger nuclease gene targeting. HV1 could be detected in medullary thick limb from wild-type rats. Intracellular acidification using an NH4Cl prepulse in 0 sodium/BaCl2 containing media resulted in superoxide production in thick limb from wild-type but not HV1(-/-) rats (P<0.05) and more rapid recovery of intracellular pH in wild-type rats (ΔpHI 0.005 versus 0.002 U/s, P=0.046, respectively). Superoxide production was enhanced by low intracellular sodium (<10 mmol/L) in both thick limb and peritoneal macrophages only when HV1 was present. When fed a high-salt diet, blood pressure, outer medullary renal injury (tubular casts), and oxidative stress (4-hydroxynonenal staining) were significantly reduced in HV1(-/-) rats compared with wild-type Dahl salt-sensitive rats. We conclude that HV1 is expressed in medullary thick ascending limb and promotes superoxide production in this segment when intracellular Na(+) is low. HV1 contributes to the development of hypertension and renal disease in Dahl salt-sensitive rats.
authors.affiliation: From the Department of Physiology (C.J, J.S., C.A.S., H.O., B.B., S.D., A.G., R.P., P.M.O.) and Department of Pharmacology and Toxicology (N.A.L.), Georgia Regents University, Augusta; Department of Physiology, Medical College of Wisconsin, Milwaukee (A.M.G., H.J.J.); and Department of Biology & Physics, Kennesaw State University, Atlanta, GA (S.M.E.S.).
authors.forename: Chunhua
authors.initials: C
authors.lastname: Jin
authors.affiliation: From the Department of Physiology (C.J, J.S., C.A.S., H.O., B.B., S.D., A.G., R.P., P.M.O.) and Department of Pharmacology and Toxicology (N.A.L.), Georgia Regents University, Augusta; Department of Physiology, Medical College of Wisconsin, Milwaukee (A.M.G., H.J.J.); and Department of Biology & Physics, Kennesaw State University, Atlanta, GA (S.M.E.S.).
authors.forename: Jingping
authors.initials: J
authors.lastname: Sun
authors.affiliation: From the Department of Physiology (C.J, J.S., C.A.S., H.O., B.B., S.D., A.G., R.P., P.M.O.) and Department of Pharmacology and Toxicology (N.A.L.), Georgia Regents University, Augusta; Department of Physiology, Medical College of Wisconsin, Milwaukee (A.M.G., H.J.J.); and Department of Biology & Physics, Kennesaw State University, Atlanta, GA (S.M.E.S.).
authors.forename: Carly A
authors.initials: CA
authors.lastname: Stilphen
authors.affiliation: From the Department of Physiology (C.J, J.S., C.A.S., H.O., B.B., S.D., A.G., R.P., P.M.O.) and Department of Pharmacology and Toxicology (N.A.L.), Georgia Regents University, Augusta; Department of Physiology, Medical College of Wisconsin, Milwaukee (A.M.G., H.J.J.); and Department of Biology & Physics, Kennesaw State University, Atlanta, GA (S.M.E.S.).
authors.forename: Susan M E
authors.initials: SM
authors.lastname: Smith
authors.affiliation: From the Department of Physiology (C.J, J.S., C.A.S., H.O., B.B., S.D., A.G., R.P., P.M.O.) and Department of Pharmacology and Toxicology (N.A.L.), Georgia Regents University, Augusta; Department of Physiology, Medical College of Wisconsin, Milwaukee (A.M.G., H.J.J.); and Department of Biology & Physics, Kennesaw State University, Atlanta, GA (S.M.E.S.).
authors.forename: Hiram
authors.initials: H
authors.lastname: Ocasio
authors.affiliation: From the Department of Physiology (C.J, J.S., C.A.S., H.O., B.B., S.D., A.G., R.P., P.M.O.) and Department of Pharmacology and Toxicology (N.A.L.), Georgia Regents University, Augusta; Department of Physiology, Medical College of Wisconsin, Milwaukee (A.M.G., H.J.J.); and Department of Biology & Physics, Kennesaw State University, Atlanta, GA (S.M.E.S.).
authors.forename: Brent
authors.initials: B
authors.lastname: Bermingham
authors.affiliation: From the Department of Physiology (C.J, J.S., C.A.S., H.O., B.B., S.D., A.G., R.P., P.M.O.) and Department of Pharmacology and Toxicology (N.A.L.), Georgia Regents University, Augusta; Department of Physiology, Medical College of Wisconsin, Milwaukee (A.M.G., H.J.J.); and Department of Biology & Physics, Kennesaw State University, Atlanta, GA (S.M.E.S.).
authors.forename: Sandip
authors.initials: S
authors.lastname: Darji
authors.affiliation: From the Department of Physiology (C.J, J.S., C.A.S., H.O., B.B., S.D., A.G., R.P., P.M.O.) and Department of Pharmacology and Toxicology (N.A.L.), Georgia Regents University, Augusta; Department of Physiology, Medical College of Wisconsin, Milwaukee (A.M.G., H.J.J.); and Department of Biology & Physics, Kennesaw State University, Atlanta, GA (S.M.E.S.).
authors.forename: Avirup
authors.initials: A
authors.lastname: Guha
authors.affiliation: From the Department of Physiology (C.J, J.S., C.A.S., H.O., B.B., S.D., A.G., R.P., P.M.O.) and Department of Pharmacology and Toxicology (N.A.L.), Georgia Regents University, Augusta; Department of Physiology, Medical College of Wisconsin, Milwaukee (A.M.G., H.J.J.); and Department of Biology & Physics, Kennesaw State University, Atlanta, GA (S.M.E.S.).
authors.forename: Roshan
authors.initials: R
authors.lastname: Patel
authors.affiliation: From the Department of Physiology (C.J, J.S., C.A.S., H.O., B.B., S.D., A.G., R.P., P.M.O.) and Department of Pharmacology and Toxicology (N.A.L.), Georgia Regents University, Augusta; Department of Physiology, Medical College of Wisconsin, Milwaukee (A.M.G., H.J.J.); and Department of Biology & Physics, Kennesaw State University, Atlanta, GA (S.M.E.S.).
authors.forename: Aron M
authors.initials: AM
authors.lastname: Geurts
authors.affiliation: From the Department of Physiology (C.J, J.S., C.A.S., H.O., B.B., S.D., A.G., R.P., P.M.O.) and Department of Pharmacology and Toxicology (N.A.L.), Georgia Regents University, Augusta; Department of Physiology, Medical College of Wisconsin, Milwaukee (A.M.G., H.J.J.); and Department of Biology & Physics, Kennesaw State University, Atlanta, GA (S.M.E.S.).
authors.forename: Howard J
authors.initials: HJ
authors.lastname: Jacob
authors.affiliation: From the Department of Physiology (C.J, J.S., C.A.S., H.O., B.B., S.D., A.G., R.P., P.M.O.) and Department of Pharmacology and Toxicology (N.A.L.), Georgia Regents University, Augusta; Department of Physiology, Medical College of Wisconsin, Milwaukee (A.M.G., H.J.J.); and Department of Biology & Physics, Kennesaw State University, Atlanta, GA (S.M.E.S.).
authors.forename: Nevin A
authors.initials: NA
authors.lastname: Lambert
authors.affiliation: From the Department of Physiology (C.J, J.S., C.A.S., H.O., B.B., S.D., A.G., R.P., P.M.O.) and Department of Pharmacology and Toxicology (N.A.L.), Georgia Regents University, Augusta; Department of Physiology, Medical College of Wisconsin, Milwaukee (A.M.G., H.J.J.); and Department of Biology & Physics, Kennesaw State University, Atlanta, GA (S.M.E.S.). paoconnor@gru.edu.
authors.forename: Paul M
authors.initials: PM
authors.lastname: O'Connor
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D006859:Hydrogen / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006973:Hypertension / Q000378:metabolism* / Q000503:physiopathology; D007473:Ion Channels / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D007674:Kidney Diseases / Q000378:metabolism* / Q000503:physiopathology; D008138:Loop of Henle / Q000166:cytology / Q000378:metabolism*; D008297:Male; D009249:NADP / Q000378:metabolism; D018408:Patch-Clamp Techniques; D051381:Rats; D020303:Rats, Inbred Dahl; D011922:Rats, Mutant Strains; D017382:Reactive Oxygen Species / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism*
chemical_list: C000592391:Hv1 proton channel, rat; D007473:Ion Channels; D017382:Reactive Oxygen Species; D013481:Superoxides; D009249:NADP; D006859:Hydrogen; D012964:Sodium
keywords: free radicals; hypertension; oxidative stress