title: Tumor necrosis factor-alpha is an endogenous inhibitor of Na+-K+-2Cl- cotransporter (NKCC2) isoform A in the thick ascending limb.
abstract: 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.
authors.affiliation: Dept. of Pharmacology, New York Medical College, Valhalla, NY 10595, USA.
authors.forename: Sailaja
authors.initials: S
authors.lastname: Battula
authors.forename: Shoujin
authors.initials: S
authors.lastname: Hao
authors.forename: Paulina L
authors.initials: PL
authors.lastname: Pedraza
authors.forename: Charles T
authors.initials: CT
authors.lastname: Stier
authors.forename: Nicholas R
authors.initials: NR
authors.lastname: Ferreri
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002712:Chlorides / Q000378:metabolism; D053938:DNA Fragmentation; D018076:DNA, Complementary / Q000096:biosynthesis; D007202:Indicators and Reagents; D007536:Isomerism; D007671:Kidney Concentrating Ability / Q000502:physiology; D007677:Kidney Function Tests; D007679:Kidney Medulla / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009994:Osmolar Concentration; D010101:Oxygen Consumption / Q000187:drug effects; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D028021:Sodium-Potassium-Chloride Symporters / Q000235:genetics / Q000378:metabolism*; D064466:Solute Carrier Family 12, Member 1; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000502:physiology*
chemical_list: D002712:Chlorides; D018076:DNA, Complementary; D007202:Indicators and Reagents; D012333:RNA, Messenger; C578714:SLC12A1 protein, human; C578715:Slc12a1 protein, mouse; D028021:Sodium-Potassium-Chloride Symporters; D064466:Solute Carrier Family 12, Member 1; D014409:Tumor Necrosis Factor-alpha