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Phenotypic effects of aldosterone and dexamethasone in a SV40‐transformed mammalian cortical ascending limb cell line exhibiting mineralocorticoid receptors
Author(s) -
Vandewalle A.,
RafestinOblin M.E.,
Hagege J.,
GéniteauLegendre M.,
Cassingéna R.,
Ronco P. M.
Publication year - 1993
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041560222
Subject(s) - aldosterone , mineralocorticoid , endocrinology , medicine , dexamethasone , mineralocorticoid receptor , glucocorticoid , glucocorticoid receptor , receptor , steroid hormone , hormone , biology , ouabain , triiodothyronine , chemistry , sodium , organic chemistry
We have analyzed the functional and morphological effects of corticosteroid hormones in a SV40‐transformed rabbit cortical‐ascending‐limb (CAL) cell line (RC.SV2, Vandewalle et al., 1989) having mineralocorticoid (MR) and glucocorticoid (GR) receptors (Rafestin‐Oblin et al., 1993). Both aldosterone and dexamethasone (5 × 10 −8 M) induced a marked increase in ( 3 H)ouabain binding (used to quantify membrane Na + ‐K + ATPase) detectable as early as 6 hours and maximal at 24 hours (+56‐57%) (due to a 1.6‐1.8‐fold increase in cell membrane binding sites without Kd alteration), and significantly augmented the ouabainsensitive component of Rb + influx. Triiodothyronine (T3, 10 −9 M) also stimulated ouabain binding by 21% but was not permissive for steroid action, whereas 5 μg/ml insulin had no effect. Both steroid hormones, T3 and insulin induced the formation of domes that was tightly correlated with ouabain binding (r = 0.949) except for insulin. The effects of aldosterone and dexamethasone on cell monolayers and cell ultrastructure were, however, strikingly different as aldosterone induced a marked amplification of basolateral areas with appearance of large intercellular spaces, reminiscent of the changes observed in deoxycorticosteronetreated rats, whereas dexamethasone predominantly influenced cell height. This discrepancy might be due to specific occupancy of MR and GR by aldosterone and dexamethasone, respectively, and/or to nongenomic effects of dexamethasone. We have thus characterized a cell culture model making it possible to analyze the actions of mineralocorticoid and glucocorticoid hormones in the mammalian kidney. © 1993 Wiley‐Liss, Inc.