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

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

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^(-6)mol/L、ALD+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6 h 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^(-7)～10^(-6)moL/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。

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.