title: Chronic furosemide or hydrochlorothiazide administration increases H+-ATPase B1 subunit abundance in rat kidney.
abstract: Furosemide administration stimulates distal acidification. This has been attributed to the increased lumen-negative voltage in the distal nephron, but the aspect of regulatory mechanisms of H(+)-ATPase has not been clear. The purpose of this study is to investigate whether chronic administration of diuretics alters the expression of H(+)-ATPase and whether electrogenic Na(+) reabsorption is involved in this process. A 7-day infusion of furosemide or hydrochlorothiazide (HCTZ) lowered urine pH significantly. However, this effect of furosemide-induced distal acidification was not changed with amiloride-blocking electrogenic Na(+) reabsorption. On immunoblotting, a polyclonal antibody against the H(+)-ATPase B1 subunit recognized a specific approximately 56-kDa band in membrane fractions from the kidney. The protein abundance of H(+)-ATPase was significantly increased by furosemide and HCTZ infusion in both the cortex and outer medulla. Furosemide plus amiloride administration also increased the H(+)-ATPase protein abundance significantly. However, no definite subcellular redistribution of H(+)-ATPase was observed by furosemide +/- amiloride infusion with immunohistochemistry. Chronic furosemide +/- amiloride administration induced a translocation of pendrin to the apical membrane, while total protein abundance was not increased. The mRNA expression of H(+)-ATPase was not altered by furosemide +/- amiloride infusion. We conclude that chronic administration of diuretics enhances distal acidification by increasing the abundance of H(+)-ATPase irrespective of electrogenic Na(+) reabsorption. This upregulation of H(+)-ATPase in the intercalated cells may be the result of tubular hypertrophy by diuretics.
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Clinical Research Institute of Seoul National University Hospital, Chongno-gu, Seoul 110-744, South Korea.
authors.forename: Ki Young
authors.initials: KY
authors.lastname: Na
authors.forename: Gheun-Ho
authors.initials: GH
authors.lastname: Kim
authors.forename: Kwon Wook
authors.initials: KW
authors.lastname: Joo
authors.forename: Jay Wook
authors.initials: JW
authors.lastname: Lee
authors.forename: Hye Ryoun
authors.initials: HR
authors.lastname: Jang
authors.forename: Yun Kyu
authors.initials: YK
authors.lastname: Oh
authors.forename: Un Sil
authors.initials: US
authors.lastname: Jeon
authors.forename: Seoung-Wan
authors.initials: SW
authors.lastname: Chae
authors.forename: Mark A
authors.initials: MA
authors.lastname: Knepper
authors.forename: Jin Suk
authors.initials: JS
authors.lastname: Han
mesh_terms: D000818:Animals; D015153:Blotting, Western; D027963:Chloride-Bicarbonate Antiporters / Q000378:metabolism; D004232:Diuretics / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D005665:Furosemide / Q000494:pharmacology*; D006852:Hydrochlorothiazide / Q000494:pharmacology*; D007150:Immunohistochemistry; D007668:Kidney / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D008297:Male; D006180:Proton-Translocating ATPases / Q000096:biosynthesis* / Q000276:immunology; D012313:RNA / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012964:Sodium / Q000378:metabolism; D000076988:Sulfate Transporters
chemical_list: D027963:Chloride-Bicarbonate Antiporters; D004232:Diuretics; C494615:Slc26A4 protein, rat; D000076988:Sulfate Transporters; D006852:Hydrochlorothiazide; D012313:RNA; D005665:Furosemide; D012964:Sodium; D006180:Proton-Translocating ATPases