Details

Autor(en) / Beteiligte

• Hanke, Craig J

Titel

Intra-adrenal regulation of zona glomerulosa cell aldosterone synthesis by endothelial cell nitric oxide production

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

2000

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• To investigate the mechanism of nitric oxide (NO) inhibition of aldosterone release, this study compared the effects of type-A natriuretic peptide to a NO-donor, DETA nonoate, on 3′5′-cyclic guanosine monophosphate (cGMP) production and angiotensin II (AII)-stimulated aldosterone synthesis in primary cultures of bovine adrenal zona glomerulosa (ZG) cells. Type-A natriuretic peptide (10−10 to 10 −6 M) and DETA nonoate (10−6 to 10 −3 M) stimulated concentration-related increases in cGMP production. Type-A natriuretic peptide and DETA nonoate attenuated AII-stimulated aldosterone production over the same concentration range that stimulated cGMP production. The selective inhibitor of soluble guanylyl cyclase, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) completely prevented DETA nonoate-stimulated cGMP production without altering the inhibitory effect of DETA nonoate on angiotensin II-stimulated steroidogenesis. DETA nonoate-derived NO produced an absorbance maximum of the mitochondrial cytochrome P450 of 453 nm and blocked the formation of the carbon monoxide-P450 complex with a characteristic absorbance maximum at 450 nm. Cell lysates of adrenal fibroblasts and ZG cells did not demonstrate immunoreactive bands to inducible NOS (iNOS) or endothelial NOS (eNOS) antibodies by western blot. Adrenal endothelial cell (EC) lysates contained a 133 kDa band which was immunoreactive to eNOS but not iNOS antibody. All-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 μM), increased AII-stimulated aldosterone synthesis to 2158 ± 45 pg/ml following AdeNOS transduction. The conclusions of this dissertation are that NO inhibits ZG cell aldosterone synthesis independent of guanylyl cyclase activation by binding to the heme of steroidogenic cytochrome P450 enzymes. Coincubation of ECs and ZG cells results in NO-mediated inhibition of aldosterone synthesis in an 8% but not 21% oxygen environment. The ECs lining the vasculature of the adrenal cortex are the primary source of NO in close proximity to the ZG cells. Finally, adenoviral transduction of ZG cells with an eNOS gene results in endogenous ZG cell NO production and aldosterone synthesis inhibition.