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Epithelial sodium channel (ENaC) and pregnancy
Author(s) -
West Crystal,
Zhang Zheng,
Ecker Goeffrey,
Masilamani Shyama
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.lb175
Subject(s) - epithelial sodium channel , endocrinology , medicine , amiloride , chemistry , sodium , in vivo , andrology , biology , microbiology and biotechnology , organic chemistry
A healthy pregnancy requires avid retention of sodium (Na) and plasma volume expansion (PVE) in order to provide adequate blood supply to the growing fetus. We performed in vivo and in vitro studies to examine the role of the amiloride‐sensitive Na channel (ENaC) in the Na retention and PVE of pregnancy. Late pregnant (LP) rats were in positive Na balance (LP= 2.45±0.11; virgin (V) = 1.15±0.26, mmol/day, p<0.05). A progressive increase in PV was seen in pregnant rats as shown by Evan's Blue dye analysis (mid pregnant (MP) =8.56 ± 0.59; LP=10.06 ± 0.46, ml p<0.05). In vivo ENaC activity was increased in LP vs V rats with a 2 fold greater net natriuretic response to ENaC blockade (benzamil). The protein abundance of a ENaC, the rate‐limiting subunit for channel formation, was increased in MP and LP rats (MP=167 ± 30; LP=168 ± 17, % of virgin rats, p<0.05). There were no differences in mRNA abundance of the ENaC subunits as demonstrated by real‐time RT‐PCR. Immunhistochemistry labeling of ENaC did not show increased cellular trafficking to the apical membrane of collecting duct cells. There was a strong tendency for benzamil to induce a greater PV loss in LP vs MP rats (MP= ‐0.840 ± 0.37; LP= ‐1.70 ± 0.40, ml p=0.06). These findings suggest that the pregnancy‐mediated increase in ENaC activity contributes to the Na retention and PVE of pregnancy. This research was supported by grants from the NHLBI (K22HL66994).