硫化氢下调大鼠主动脉L-精氨酸/一氧化氮合酶/一氧化氮通路

Hydrogen sulfide down-regulation of L-arginine/nitric oxide synthase/NO pathway in aortic tissues of rat

目的 观察H2S对血管L-精氨酸/一氧化氮（L-Arg/NO）通路的影响以探讨H2S和NO这两种气体信号分子间的相互作用。方法 离体孵育大鼠主动脉薄片, 加入H2S供体NaHS（10^-7～10^-4 mol·L^-1）孵育4 h,及50 μmol·L^-1NaHS分别孵育2、4和6 h.采用Greiss法测定血管亚硝酸盐含量；同位素示踪法检测血管组织一氧化氮合酶（NOS）活性及L-Arg转运, RT-PCR检测eNOS、CAT1基因表达。结果 一次性给予50 μmol·L^-1NaHS,孵育2 h,孵育液中NO2-含量比对照组低62%,血管NOS活性下降48%,L-Arg转运减少50%（P〈0.01）;孵育6 h,NO2-含量比对照组低19%（P〈0.05）,而NOS活性和L-Arg转运已基本恢复（P〉0.05）.NaHS（10^-7～10^-4 mol·L^-1）,呈浓度依赖的抑制了L-Arg/NOS/NO通路,IC50分别为0.499、3.198及3.927 μmol·L-1（P〈0.01）；而给予50 μmol·L^-1NaHS后，eNOS和CAT-1A的mRNA表达分别减少34.3%和55.1%（P〈0.01）。结论 H2S通过抑制血管组织L-Arg转运和NOS活性和基因表达,下调L-Arg/NOS/NO通路,从而减少血管NO生成。

Abstract： Aim To observe the influence of hydrogen sulfide on L-arginine/nitric oxide synthase （NOS）/NO pathway,explore the interaction between H2S and NO as cardiovascular regulatory gasotransmitters. Methods Aortic thin slices in vitro were administrated with NariS（ 10^-7 mol · L^-1 - 10^-4 mol · L^-1 ） , a donor of H2S, and incubated for 4 hours, or 50 μmol · L^-1 Naris and incubated for 2 h, 4 h and 6 h, respectively. The nitrite production Was measured with greiss assay; NOS activity and L-arginine transportation,with isotope tracer method; the eNOS and CAT1-A gene expression, with RT-PCR. Results After being given with NariS（50 μmol · L^-1 ） one time, and incubating for 2 h, the nitrite production decreased by 62% , NOS activity reduced by 48% and L-arginine transport decreased by 50%. After incubation for 6 h, the nitrite production further was inhibited by 19% （ P 〈 0. 05 ） , but NOS activity and L-arginine transporta were recovered to a large extert （P 〉0.05）. NariS（ 10^-7 mol· L^-1 - 10^-4 mol · L^-1 ） inhibited the L-arginine/NOS/ NO pathway in a dose-dependent manner, and IC50 was 0.499,3. 198 and 3.927 μmol · L^-1（p〈0.01）, respectively. The amount of eNOS and CAT-1 mRNA reduced by 34.3% and 55.1% （P〈0.01） after admistration of 50 μmol · L^-1 NariS. Conclusion H2S inhibits NO release by inhibiting L-arginine transport, NOS activity, CAT-1 and eNOS gene expression, and down-regulating L-arginine/NOS/NO pathway in aortic vessels of rat.