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Aldosterone increases BK channel trafficking in human embryonic kidney cells
Author(s) -
Bari Muhammad R,
Grimm Paul R.,
Settles Deann C.,
Foutz Ruth M.,
Holtzclaw David,
Sansom Steven C.
Publication year - 2008
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.22.1_supplement.1158.21
Subject(s) - aldosterone , bk channel , chemistry , endocrinology , medicine , patch clamp , hek 293 cells , nephron , microbiology and biotechnology , kidney , receptor , potassium channel , biology , biochemistry
Large conductance Ca 2+ ‐sensitive K + channels (BK) reside in the distal nephron where they secrete K + when the rate of distal flow is increased. A recent study showed that aldosterone (aldo) stimulated BK‐mediated K + secretion in an isolated mouse distal colon preparation. We used HEK293 cells, expressing BK channels, to determine whether aldo increases the number of BK channels in the plasma membrane by a non‐genomic mechanism. Immunocytochemistry, immunoblotting and RT‐PCR confirmed that HEK293 cells contain mineralocorticoid receptors (MR). Using single channel patch clamp analysis, we determined the 30 min. application of aldo (10 nM) on the NPo (total open time of all channels in a patch), and the percent of observed channels per patch. In cell attached patches (−Vp = −40 mV), aldo increased the NPo of BK from 0.71±0.05 to 1.84±0.41 (p=<0.05, n=3) and the percent of observed BK per patch from 58% to 71% (p<0.05, n=4). Treating cells with aldo plus spironolactone, a MR antagonist, reduced the number of detected BK channels to 50% (p<0.05, n=3). The aldo‐treated cells showed an increased quantity of cell surface biotinylated BK (OD, 1.46±0.19 in control and 3.87±0.76 with aldo, p<0.05, n=3) that was inhibited to OD, 1.32±0.35 by 5 μg/ml brefeldin‐A (p<0.05, n=3). These data suggest that aldosterone, via MR, increases the trafficking of expressed BK channels from the ER to the apical membrane of HEK293 cells. Grant support: NIH RO1‐DK49561 and AHA 0610059Z.