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.

The Anion Exchanger Pendrin (SLC26A4) and Renal Acid-base Homeostasis

“…In rats treated for 7 days with furosemide and substitution of salt and potassium with drinking water, no obvious hypokalemia or metabolic alkalosis developed but pendrin subcellular localization was shifted from a more cytosolic pool to the luminal membrane together with increased expression of H + -ATPases [58]. A third model of metabolic alkalosis was reported by Wang et al, inducing hypercalcemic metabolic alkalosis in rats with PTH infusions.…”

Alkali Therapy Attenuates the Progression of Kidney Injury via Na/H Exchanger Inhibition in 5/6 Nephrectomized Rats

“…Affinity-purified polyclonal antibodies against NHE3, NKCC2, NCC, ENaC-α, ENaC-γ, NBC, pendrin, and H-ATPase were used as described in a previous study (7, 14). Affinity-purified polyclonal antibodies against Na-glucose cotransporter-1 (SGLT1; AB1352; Millipore Corp., Billerica, MA, USA), ENaC-β (sc-21013; Santa Cruz Biotechnology, Inc., Santa Cruz, CA, USA), and Na-K-ATPase (05-396; Millipore Corp.) were also used.…”

Changes in the Sodium and Potassium Transporters in the Course of Chronic Renal Failure

“…Finally, protein concentrations were corrected to reflect these measurements. They were subjected to immunoblot analysis as described previously [19]. …”