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Application of lymphocytes as model for proteolytic activation of ENaC
Author(s) -
Friis Ulla G,
Bistrup Claus,
Jensen Boye L
Publication year - 2009
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.23.1_supplement.604.8
Subject(s) - epithelial sodium channel , amiloride , proteases , urine , endocrinology , plasmin , medicine , chemistry , serine protease , sodium , pharmacology , biochemistry , protease , enzyme , organic chemistry
We have recently identified plasmin as an activator of epithelial Na+ channels (ENaC) in urine from humans and rats with nephrotic syndrome (1). Lymphocytes express ENaC similarly to ENaC in renal principal cells. We therefore wanted to study if human lymphocytes could be used as a model for proteolytic activation of ENaC. Human lymphocytes were isolated from peripheral blood samples from healthy young males. When lymphocytes were flushed with urine from control rats, it did not significantly increase sodium currents, while when flushed with urine collected on day 4 after puromycin injection resulted in a 4.24 ± 0.97 fold increase in the sodium current compared to controls (control ‐77 ± 11 pA vs. nephrotic urine ‐240 ± 17 pA, n=4, P <0.005). The stimulatory effect was blocked by pre‐treatment of nephrotic urine with aprotinin (700 μg/mL), which is an inhibitor of serine proteases. The identity of the sodium current was further established by blockade of the current with 2 μmol/L amiloride, which is specific for ENaC inhibition when used in this concentration. These data thus confirm the applicability of lymphocytes in the study of ENaC. This study was supported by grants from the Danish Research Agency and the Novo Nordisk Foundation. (1) Svenningsen S et al. JASN: in press.