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Altered expression of renal acid-base transporters in rats with lithium-induced NDI.

Authors: Kim, YH  Kwon, TH  Christensen, BM  Nielsen, J  Wall, SM  Madsen, KM  Frokiaer, J  Nielsen, S 
Citation: Kim YH, etal., Am J Physiol Renal Physiol. 2003 Dec;285(6):F1244-57. Epub 2003 Aug 26.
Pubmed: (View Article at PubMed) PMID:12944321
DOI: Full-text: DOI:10.1152/ajprenal.00176.2003

Prolonged lithium treatment of humans and rodents often results in hyperchloremic metabolic acidosis. This is thought to be caused by diminished net H+ secretion and/or excessive back-diffusion of acid equivalents. To explore whether lithium treatment is associated with changes in the expression of key renal acid-base transporters, semiquantitative immunoblotting and immunocytochemistry were performed using kidneys from lithium-treated (n = 6) and control (n = 6) rats. Rats treated with lithium for 28 days showed decreased urine pH, whereas no significant differences in blood pH and plasma HCO3- levels were observed. Immunoblot analysis revealed that lithium treatment induced a significant increase in the expression of the H+-ATPase (B1-subunit) in cortex (190 +/- 18%) and inner stripe of the outer medulla (190 +/- 9%), and a dramatic increase in inner medulla (900 +/- 104%) in parallel to an increase in the expression of type 1 anion exchanger (400 +/- 40%). This was confirmed by immunocytochemistry and immunoelectron microscopy, which also revealed increased density of intercalated cells. Moreover, immunoblotting and immunocytochemistry revealed a significant increase in the expression of the type 1 electrogenic Na+-HCO3- cotransporter (NBC) in cortex (200 +/- 23%) and of the electroneutral NBCn1 in inner stripe of the outer medulla (250 +/- 54%). In contrast, there were no changes in the expression of Na+/H+ exchanger-3 or of the Cl-/HCO3- exchanger pendrin. These results demonstrate that the expression of specific renal acid-base transporters is markedly altered in response to long-term lithium treatment. This is likely to represent direct or compensatory effects to increase the capacity for HCO3- reabsorption, NH4+ reabsorption, and proton secretion to prevent the development of systemic metabolic acidosis.

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CRRD Object Information
CRRD ID: 1600034
Created: 2007-02-26
Species: All species
Last Modified: 2007-02-26
Status: ACTIVE



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