Cloning, renal distribution, and regulation of the rat Na+-HCO3- cotransporter.
We recently reported the cloning and expression of a human kidney Na+-HCO3- cotransporter (NBC-1) (C. E. Burnham, H. Amlal, Z. Wang, G. E. Shull, and M. Soleimani. J. Biol. Chem. 272: 19111-19114, 1997). To expedite in vivo experimentation, we now report the cDNA sequence of rat kidney NBC-1. In addition, we describe both the organ and nephron segment distributions and the regulation of NBC-1 mRNA under three models of pH stress: chloride-depletion alkalosis (CDA), metabolic acidosis, and bicarbonate loading. Rat NBC-1 cDNA encodes an open reading frame of 1,035 amino acids, with 96 and 87% identity to human and salamander NBC-1, respectively. Rat NBC-1 mRNA is expressed at high levels in kidney and brain, with lower levels in colon, stomach, and heart. None appears in liver. In the kidney, NBC-1 is expressed mainly in the proximal tubule, with traces found in medullary thick ascending limb and papilla. HCO3- loading decreased NBC-1 mRNA levels, which were unchanged either by metabolic acidosis or by CDA.
Burnham
C E
CE
Department of Medicine, University of Cincinnati School of Medicine, Cincinnati, Ohio 45267-0585, USA.
Flagella
M
M
Wang
Z
Z
Amlal
H
H
Shull
G E
GE
Soleimani
M
M
D000138:Acidosis / Q000378:metabolism; D000471:Alkalosis / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D008969:Molecular Sequence Data; D051381:Rats; D027982:Sodium-Bicarbonate Symporters; D014018:Tissue Distribution
D002352:Carrier Proteins; D018076:DNA, Complementary; D027982:Sodium-Bicarbonate Symporters