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The Sodium‐Activated Sodium Channel (Nax) present in kidney thick ascending limb and collecting duct cells is augmented during high salt intake
Author(s) -
Lara Lucienne S.,
Gonzalez Alexis A.,
Bourgeois Camille,
Zsombok Andrea,
Prieto Minolfa C.,
Navar L. Gabriel
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.1039.30
Subject(s) - western blot , sodium , chemistry , medicine , kidney , endocrinology , extracellular , oxidative stress , loop of henle , downregulation and upregulation , extracellular fluid , biology , biochemistry , nephron , organic chemistry , gene
Increased dietary salt triggers oxidative stress and exacerbates hypertension and kidney injury in Ang II dependent hypertension but the mechanism for detecting increased salt intake remains unclear. A Na + ‐activated Na + channel (Na x ) recently discovered in the brain operates as a sensor of extracellular fluid Na + concentration. We have identified a specific RT‐PCR product of 448 bp with a Western blot band of 190 KDa demonstrating the presence of the Na x in the rat kidneys. In addition, immunofluorescence staining localized Na x on the luminal side of tubule cells co‐localizing with AQP‐2, a marker of principal cells, and with Tamm‐Horsfall, a marker for the thick ascending limb (TAL). To determine if high salt diet (HSD) increases the Na x expression, 15 male Sprague‐Dawley rats (175–200 g) were randomly divided in 2 groups: control (n=5) and HSD – rats subjected to 8% high salt diet for 7 and 14 days (n=5; each subgroup). Medullary protein extracts were used for Western blot analysis. We observed that 7 days HSD increased the Na x expression 74±16 % (p<0.05) but was similar to control levels at 14 days. Collectively, these data suggest that Na x localized in collecting ducts and ascending loops is upregulated by HSD suggesting a role in monitoring changes in tubular fluid Na + concentration. NIH [IdeA Program (P20RR01765906); Tulane‐BIRCWH Program (K12HGO4351)] and AHA (09PRE2209079; 09BGIA2280440)