Inhibition of Adrenal Cell Aldosterone Synthesis by Endogenous Nitric Oxide Release

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Abstract
Abstract —Adrenal zona glomerulosa (ZG) cells do not contain nitric oxide (NO) synthase (NOS). We conferred endothelial NOS activity onto adrenal ZG cells through transduction with a recombinant adenovirus encoding the endothelial NOS gene (AdeNOS) to determine the effect of endogenous NO on aldosterone synthesis. A 135-kDa protein band immunoreactive to anti–endothelial NOS antibody was observed in Western blots of AdeNOS-transduced ZG cells but not in control cells or cells transduced with adenovirus encoding the β-galactosidase gene (AdβGal). Nitrate/nitrite production in AdeNOS-transduced ZG cells increased from 0.15±0.01 to 0.27±0.01 μmol/L after stimulation with 1 nmol/L angiotensin II. The treatment of AdeNOS-transduced cells with 30 μmol/L l -nitro-arginine decreased angiotensin II–stimulated nitrite production from 0.27±0.01 to 0.17±0.01 μmol/L. Basal and angiotensin II–stimulated nitrite production was not increased in AdβGal-transduced or control cells. AdeNOS-transduced cells demonstrated diaminofluorescein-2 diacetate fluorescence, which was blocked by pretreatment with l -nitro-arginine. Angiotensin II–stimulated aldosterone synthesis decreased from 5123±177 pg/mL in AdβGal-transduced ZG cells to 72±27 pg/mL in AdeNOS-transduced cells. Treatment with the NOS inhibitor thiocitrulline (30 μmol/L) increased angiotensin II–stimulated aldosterone synthesis to 2158±45 pg/mL after AdeNOS transduction. These data demonstrate that adenovirus-mediated gene transfer of eNOS in ZG cells results in the expression of active endothelial NOS enzyme and that this endogenous NO production by ZG cells decreases aldosterone synthesis.