In fetal pneumocytes, increasing P(O(2)) can raise apical Na(+) conductance (G(Na(+))) and increase the abundance of epithelial Na(+) channel subunit (alpha-, beta-, and gamma-ENaC) mRNA, suggesting that the rise in G(Na(+)), which may be important to the perinatal maturation of the lung, reflects O(2)-evoked ENaC gene expression. However, we now show that physiologically relevant increases in P(O(2)) do not affect alpha-, beta-, and gamma-ENaC mRNA abundance in pneumocytes maintained (approximately 48 h) in hormone-free medium or in medium supplemented with dexamethasone and tri-iodothyronine, although the response does persist in cells maintained in medium containing a complex mixture of hormones/growth factors. However, parallel electrometric studies revealed clear increases in G(Na(+)) under all tested conditions and so it is now clear that O(2)-evoked increases in G(Na(+)) can occur without corresponding increases in ENaC mRNA abundance. It is therefore unlikely that this rise in G(Na(+)) is secondary to O(2)-evoked ENaC gene expression.
|Number of pages||6|
|Journal||Biochemical and Biophysical Research Communications|
|Publication status||Published - 2003|
Richard, K., Ramminger, S. J., Inglis, S. K., Olver, R. E., Land, S. C., & Wilson, S. M. (2003). O2 can raise fetal pneumocyte Na+ conductance without affecting ENaC mRNA abundance. Biochemical and Biophysical Research Communications, 305(3), 671-6. https://doi.org/10.1016/S0006-291X(03)00832-5