Premium
Inhibitory effects of digoxin and ouabain on aldosterone synthesis in human adrenocortical NCI‐H295 cells
Author(s) -
Kau MeiMei,
Kan ShuFen,
Wang JiingRong,
Wang Paulus S.
Publication year - 2005
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.20415
Subject(s) - ouabain , digoxin , aldosterone , endocrinology , medicine , steroidogenic acute regulatory protein , chemistry , aldosterone synthase , cytochrome p450 , cholesterol side chain cleavage enzyme , renin–angiotensin system , biology , gene expression , metabolism , biochemistry , sodium , heart failure , organic chemistry , gene , blood pressure
The present study was to investigate the effects and action mechanisms of digoxin and ouabain on steroidogenesis in human adrenocortical NCI‐H295 cells. Administration of digoxin or ouabain for 24 h decreased the basal and angiotensin II (Ang II)‐stimulated release of aldosterone by NCI‐H295 cells. The conversions of corticosterone (substrate of cytochrome P450 aldosterone synthase, P450c11AS) to aldosterone or deoxycortisol (substrate of cytochrome P450 11β‐hydroxylase, P450c11β) to cortisol were reduced by digoxin or ouabain. The basal and 22‐hydroxy‐cholesterol (a membrane‐permeable cholesterol, substrate of cytochrome P450 side‐chain cleavage enzyme, P450scc)‐stimulated pregnenolone release in mitochondria was inhibited by digoxin or ouabain. Digoxin or ouabain suppressed the basal and Ang II‐stimulated protein expression of steroidogenic acute regulatory (StAR) protein and P450scc. Incubation of digoxin or ouabain for 24 h reduced P450c11AS mRNA expression in NCI‐H295 cells. Digoxin or ouabain (10 −6 M, 24 h)‐treated cells showed a lower resting intracellular Ca 2+ concentration ([Ca 2+ ] i ) and an attenuated response of [Ca 2+ ] i to Ang II. Since no significant cytotoxicity was observed at 10 −6 M digoxin or ouabain, the digoxin‐ or ouabain‐induced decrease of aldosterone or cortisol release was not associated with cytotoxicity. These results demonstrate that digoxin or ouabain inhibits the aldosterone or cortisol release via reduction of P450c11AS or P450c11β and P450scc activities, inhibition of StAR and P450scc protein expression, suppression of P450c11AS mRNA expression, and attenuation of Ca 2+ mobilization in NCI‐H295 cells. © 2005 Wiley‐Liss, Inc.