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Developmental changes in the ENaC channel of the chick chorioallantoic membrane
Author(s) -
Gonzalez Laura A.,
Silverthorn Dee U
Publication year - 2010
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.24.1_supplement.611.12
Subject(s) - epithelial sodium channel , amiloride , reabsorption , aldosterone , medicine , endocrinology , biology , chorioallantoic membrane , hormone , microbiology and biotechnology , ouabain , epithelium , sodium , embryo , chemistry , kidney , genetics , organic chemistry
Confined to the closed system of the egg, the chick embryo deposits its renal wastes into the chorioallantoic sac, an outgrowth of its hindgut. The allantoic fluid undergoes changes in both volume and ion composition throughout the development of the embryo. These changes are most likely the result of Na + reabsorption from the allantoic fluid. In previous experiments we demonstrated that short‐circuit current across the epithelia increases five‐fold between embryonic days 9–19. This current is inhibitable by ouabain and amiloride, indicating that Na + ‐K + ‐ATPase and ENaC channels play a role. Aldosterone increased the amiloride‐inhibitable current from day 9 to day 18, suggesting that the ENaC channels may be up‐regulated by the hormone. The slow (100 min) aldosterone response appears to be the classic gene‐regulated response to a steroid hormone. In this study we are investigating the role of the epithelial sodium channel ENaC in allantoic short‐circuit current. We used RT‐PCR to measure normal developmental changes in the RNA message of the three ENaC subunits in the allantoic epithelium. The RNA message of all subunits increased two‐fold from day 9 to day 11, and then slowly decreased from days 11 to 17. These data were confirmed using Western blots. Subsequent experiments will investigate the role of aldosterone in inducing ENaC protein synthesis.