醛固酮对血管外膜诱导型一氧化氮合酶/一氧化氮通路影响的实验研究

目的观察醛固酮对血管外膜诱导型一氧化氮合酶（iNOS）／一氧化氮（NO）通路的影响及作用机制。方法取sD大鼠胸主动脉外膜,分别给予不同浓度醛固酮（ALD）10^-8～10^-6mol／L、ALl）＋螺内酯以及ALD＋RU486进行孵育,此外在给予脂多糖激活血管外膜iNOS／NO的情况下,观察以上各组药物刺激后iNOS／NO系统的变化。与上述药物共同孵育6h后通过Griess法测定相对稳定的代谢产物硝酸盐和亚硝酸盐（NOx）代表NO的产生量,采用[^3H]-L-精氨酸标记的同位素法测定外膜iNOS活性。结果（1）NOx产生的变化：ALD刺激后血管外膜NOx生成无明显变化。用螺内酯拮抗盐皮质激素受体后,高浓度ALD组（10～～10^-6mol／L）血管外膜NOx产生呈下降趋势（P〈0．05）。用RU486拮抗糖皮质激素受体后随ALD浓度增加NOx生成量也呈浓度依赖性增加（P〈0．01）。脂多糖刺激后上述趋势更为明显。（2）iNOS活性的变化：ALD刺激后iNOS活性无明显变化,螺内酯刺激后血管外膜iNOS活性有下降趋势,但无统计学意义。而RU486刺激后血管外膜iNOS活性显著增加（P〈0．05）。同时给予脂多糖刺激后,螺内酯＋ALD组血管外膜iNOS活性显著下降（P〈0．01）,ALD＋RU486组血管外膜iNOS活性显著增加（p〈0．05）。结论ALD主要通过盐皮质激素受体和糖皮质激素受体通路两种途径直接影响血管外膜iNOS／NO系统,醛固酮作用于盐皮质激素受体能够诱导iNOS激活、刺激NO产生,作用于糖皮质激素受体抑制iNOS／NO激活。

Effects of aldosterone on inducible nitric oxide synthase/nitric oxide pathway in aortic adventitia

OBJECTIVE: 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. METHODS: 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 detemined by isotope-labeled L-arginine convertion rate. RESULTS: (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). CONCLUSION: Aldosterone has a dual effect on iNOS/NO through mineralocorticoid receptor and glucocorticoid receptor pathway.