Chronic metabolic acidosis increases NaDC-1 mRNA and protein abundance in rat kidney.
BACKGROUND
Chronic metabolic acidosis increases, while alkali feeding inhibits, proximal tubule citrate absorption. The activity of the apical membrane Na+/citrate cotransporter is increased in metabolic acidosis, but is not altered by alkali feeding.


METHODS
Renal cortical mRNA and brush border membrane protein abundances of sodium/dicarboxylate-1 (NaDC-1), the apical membrane Na+/citrate transporter, were measured.


RESULTS
By immunohistochemistry, NaDC-1 was localized to the apical membrane of the proximal tubule. Chronic metabolic acidosis caused an increase in NaDC-1 protein abundance that was maximal in the S2 segment and that increased with time. Metabolic acidosis also increased NaDC-1 mRNA abundance, but this was first seen at three hours and correlated with the severity of the metabolic acidosis. Alkali feeding had no effect on NaDC-1 protein or mRNA abundance.


CONCLUSIONS
Chronic metabolic acidosis increases renal cortical NaDC-1 mRNA abundance and apical membrane NaDC-1 protein abundance, while alkali feeding is without effect on NaDC-1.
Aruga
S
S
Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas 75390-9003, USA.
Wehrli
S
S
Kaissling
B
B
Moe
O W
OW
Preisig
P A
PA
Pajor
A M
AM
Alpern
R J
RJ
D000138:Acidosis / Q000139:chemically induced / Q000378:metabolism*; D000143:Acids / Q000494:pharmacology; D000208:Acute Disease; D000468:Alkalies / Q000494:pharmacology; D000643:Ammonium Chloride / Q000494:pharmacology; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism*; D002908:Chronic Disease; D002951:Citrates / Q000652:urine; D029382:Dicarboxylic Acid Transporters; D015870:Gene Expression / Q000502:physiology; D007672:Kidney Cortex / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D029363:Organic Anion Transporters, Sodium-Dependent; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017693:Sodium Bicarbonate / Q000494:pharmacology; D027981:Symporters
D000143:Acids; D000468:Alkalies; D002352:Carrier Proteins; D002951:Citrates; D029382:Dicarboxylic Acid Transporters; D008565:Membrane Proteins; D029363:Organic Anion Transporters, Sodium-Dependent; D012333:RNA, Messenger; C092524:SLC13A2 protein, human; C490478:Slc13a2 protein, rat; D027981:Symporters; D000643:Ammonium Chloride; D017693:Sodium Bicarbonate