ABSTRACT
<p><b>OBJECTIVE</b>To evaluate the effect and related mechanisms of aldosterone (ALD) on inducible nitric oxide synthase (iNOS) activity and nitric oxide (NO) production in aortic adventitia.</p><p><b>METHODS</b>Aortic adventitias from SD rats were incubated for 6 hours with various protocols: buffer alone (control), ALD (10(-8) mol/L - 10(-6) mol/L), ALD + spironolactone (10(-5) mol/L, ALD + SP), ALD + RU486 (10(-5) mol/L), LPS 10 ng/ml (LPS), ALD + LPS (10 ng/ml), ALD + LPS + SP (10(-5) mol/L), and ALD + LPS + RU486. Nitrate/nitrite (NOx), an index of NO production, was measured by Greiss Reaction. iNOS activity was determined by isotope-labeled L-arginine convertion rate.</p><p><b>RESULTS</b>(1) NOx production and iNOS activity were similar between ALD and control groups (P > 0.05). NOx production was significantly reduced while iNOS activity remained unchanged in the ALD (10(-6) mol/L) + SP group compared to ALD (10(-6) mol/L) group. NOx production by 10(-7) mol/L and 10(-6) mol/L ALD increased by 50.0% and 58.7% respectively (P < 0.01) and iNOS activity was also significantly increased (P < 0.01) in ALD + RU486 group than that in ALD group. (2) LPS significantly increased the NOx production and iNOS activity (P < 0.01) and these effects were not augmented by adding ALD to LPS (P > 0.05) and SP significantly blocked and RU486 significantly enhanced the effects by LSP and ALD on NOx production and iNOS activity (P < 0.05).</p><p><b>CONCLUSION</b>Aldosterone has a dual effect on iNOS/NO through mineralocorticoid receptor and glucocorticoid receptor pathway.</p>