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Enhanced ENaC and K Ca 3.1 expression by hydrocortisone increases Na + absorption in human mammary epithelial cells.
Author(s) -
O'Grady Scott M,
Schiller Katherine R,
Maniak Peter J
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.998.11
Subject(s) - epithelial sodium channel , endocrinology , medicine , stimulation , hydrocortisone , chemistry , receptor , apical membrane , potassium channel , messenger rna , sodium , biology , biochemistry , gene , membrane , organic chemistry
Immortalized human mammary epithelial cells express apical ENaC sodium channels and basolateral K Ca 3.1 potassium channels. Treatment of monolayers with hydrocortisone (0.5 μg/ml) for 48 hours enhanced mRNA expression for α, β and γ ENaC subunits by 7.3, 10.5 and 9.6 fold as determined by quantitative RT‐PCR. Additionally, K Ca 3.1 mRNA expression was enhanced by hydrocortisone by 8.1 fold, however no increase in mRNA expression was detected for the BK (Slo1) potassium channel, which had a higher basal level of expression than K Ca 3.1 (Slo1 C T = 23.8; K Ca 3.1 C T = 27.7). Hydrocortisone also increased expression of the P2Y 6 receptor by 5.5 fold without significantly altering P2Y 1 , P2Y 2 or P2Y 4 receptor expression. Basolateral stimulation of hydrocortisone pretreated monolayers with UTP (10 μM) resulted in a significantly greater increase in short circuit current (Isc) compared to untreated control monolayers (peak ΔIsc + hydrocortisone = 20 ± 1 μA, control = 9.5 ± 2 μA). In addition, the duration of the Isc response was significantly lower in the absence of hydrocortisone with less oscillation. These results indicate that K Ca 3.1 and P2Y 6 receptor expression are up‐regulated in parallel with ENaC channels in the presence of hydrocortisone resulting in enhanced electrogenic Na + absorption following basolateral stimulation with UTP.