Changes in the sodium and potassium transporters in the course of chronic renal failure.
BACKGROUND
In chronic renal failure (CRF), residual nephrons can increase their excretion of sodium (Na) and potassium (K). However, the mechanisms of renal Na and K regulation in late-stage CRF have not been clearly investigated.


METHODS
We examined altered expression of major renal Na and K transporters in Sprague-Dawley rats at 4 and 12 weeks after a 5/6 nephrectomy.


RESULTS
CRF rats were azotemic and had gradually increased levels of urinary Na and K excretion over time. At 4 weeks, the abundance of Na-K-2Cl cotransporter (NKCC2), and Na-Cl cotransporter (NCC) in CRF rats increased significantly (477 and 222% of the control, respectively). In contrast, expression of NKCC2 and NCC decreased markedly at 12 weeks (55.4 and 30.8%, respectively). Expression of epithelial Na channel-alpha increased throughout the whole period. The abundance of renal outer medullary K-channel (ROMK) and Na-K-ATPase did not decrease at 4 weeks, but it was reduced at 12 weeks.


CONCLUSIONS
We suggest that increased urinary Na excretion in late-stage CRF may be associated with decreased expression of renal Na transporters except ENaC compared to early-stage CRF, and that increased urinary K excretion in the late stage of CRF may not be related to expression of ROMK.
Kim
Sejoong
S
Department of Internal Medicine, Gachon University of Medicine and Science, Incheon, Korea.
Heo
Nam Ju
NJ
Jung
Ji Yong
JY
Son
Min-Jeong
MJ
Jang
Hye Ryoun
HR
Lee
Jay Wook
JW
Oh
Yun Kyu
YK
Na
Ki Young
KY
Joo
Kwon Wook
KW
Han
Jin Suk
JS
D000818:Animals; D053503:Epithelial Sodium Channels / Q000378:metabolism*; D007676:Kidney Failure, Chronic / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D049992:Sodium Chloride Symporters / Q000378:metabolism*; D028021:Sodium-Potassium-Chloride Symporters / Q000378:metabolism*; D064466:Solute Carrier Family 12, Member 1; D014018:Tissue Distribution
D053503:Epithelial Sodium Channels; C510692:Kcnj1 protein, rat; D024661:Potassium Channels, Inwardly Rectifying; C578716:Slc12a1 protein, rat; D049992:Sodium Chloride Symporters; D028021:Sodium-Potassium-Chloride Symporters; D064466:Solute Carrier Family 12, Member 1