Chronic furosemide or hydrochlorothiazide administration increases H+-ATPase B1 subunit abundance in rat kidney.
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.
Na
Ki Young
KY
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.
Kim
Gheun-Ho
GH
Joo
Kwon Wook
KW
Lee
Jay Wook
JW
Jang
Hye Ryoun
HR
Oh
Yun Kyu
YK
Jeon
Un Sil
US
Chae
Seoung-Wan
SW
Knepper
Mark A
MA
Han
Jin Suk
JS
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
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