Tumor necrosis factor-alpha is an endogenous inhibitor of Na+-K+-2Cl- cotransporter (NKCC2) isoform A in the thick ascending limb

Am J Physiol Renal Physiol. 2011 Jul;301(1):F94-100. doi: 10.1152/ajprenal.00650.2010. Epub 2011 Apr 20.


The effects of TNF gene deletion on renal Na(+)-K(+)-2Cl(-) cotransporter (NKCC2) expression and activity were determined. Outer medulla from TNF(-/-) mice exhibited a twofold increase in total NKCC2 protein expression compared with wild-type (WT) mice. This increase was not observed in TNF(-/-) mice treated with recombinant human TNF (hTNF) for 7 days. Administration of hTNF had no effect on total NKCC2 expression in WT mice. A fourfold increase in NKCC2A mRNA accumulation was observed in outer medulla from TNF(-/-) compared with WT mice; NKCC2F and NKCC2B mRNA accumulation was similar between genotypes. The increase in NKCC2A mRNA accumulation was attenuated when TNF(-/-) mice were treated with hTNF. Bumetanide-sensitive O(2) consumption, an in vitro correlate of NKCC2 activity, was 2.8 ± 0.2 nmol·min(-1)·mg(-1) in medullary thick ascending limb tubules from WT, representing ∼40% of total O(2) consumption, whereas, in medullary thick ascending limb tubules from TNF(-/-) mice, it was 5.6 ± 0.3 nmol·min(-1)·mg(-1), representing ∼60% of total O(2) consumption. Administration of hTNF to TNF(-/-) mice restored the bumetanide-sensitive component to ∼30% of total O(2) consumption. Ambient urine osmolality was higher in TNF(-/-) compared with WT mice (2,072 ± 104 vs. 1,696 ± 153 mosmol/kgH(2)O, P < 0.05). The diluting ability of the kidney, assessed by measuring urine osmolality before and after 1 h of water loading also was greater in TNF(-/-) compared with WT mice (174 ± 38 and 465 ± 81 mosmol/kgH(2)O, respectively, P < 0.01). Collectively, these findings suggest that TNF plays a role as an endogenous inhibitor of NKCC2 expression and function.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Blotting, Western
  • Chlorides / metabolism
  • DNA Fragmentation
  • DNA, Complementary / biosynthesis
  • Indicators and Reagents
  • Isomerism
  • Kidney Concentrating Ability / physiology
  • Kidney Function Tests
  • Kidney Medulla / cytology
  • Kidney Medulla / drug effects
  • Kidney Medulla / metabolism*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Osmolar Concentration
  • Oxygen Consumption / drug effects
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / genetics
  • Sodium-Potassium-Chloride Symporters / genetics
  • Sodium-Potassium-Chloride Symporters / metabolism*
  • Solute Carrier Family 12, Member 1
  • Tumor Necrosis Factor-alpha / genetics
  • Tumor Necrosis Factor-alpha / physiology*


  • Chlorides
  • DNA, Complementary
  • Indicators and Reagents
  • RNA, Messenger
  • SLC12A1 protein, human
  • Slc12a1 protein, mouse
  • Sodium-Potassium-Chloride Symporters
  • Solute Carrier Family 12, Member 1
  • Tumor Necrosis Factor-alpha