新型气体信号分子硫化氢对左向右分流大鼠一氧化氮/一氧化氮合酶体系的影响

Impact of hydrogen sulfide, a novel gaseous signal molecule on nitric oxide/nitric oxide synthase pathway in left-to-right shunt: experiment with rats

目的探讨内源性硫化氢(H2S)对左向右分流大鼠一氧化氮(NO)/一氧化氮合酶(NOS)体系的影响。方法将雄性SD大鼠随机分为分流组,分流+炔丙基甘氨酸(PPG)组,假手术组和假手术组+PPG组,每组8只。分流组及分流+PPG组大鼠经腹主动脉-下腔静脉穿刺建立左向右分流动物模型。术后4周,测量大鼠平均肺动脉压(MPAP);测定血浆NO、肺组织H2S、NO含量及NOS活性;用Western印迹方法测定肺组织eNOS含量。结果分流术后4周,分流组与假手术组比较,大鼠MPAP无明显变化;分流组与假手术组比较血浆NO(23·2μmol/L±3·6μmol/Lvs17·9μmol/L±3·4μmol/L,P<0·05)、肺组织H2S(37·6μmol/mg±2·1μmol/mgvs14·4μmol/mg±1·8μmol/mg,P<0·05)、肺组织NO(38·5±6·5μmol/μgvs31·8±6·5μmol/μg,P<0·05)、肺组织NOS活性(15·1U/mg±2·4U/mgvs12·0U/mg±1·4U/mg,P<0·05)及肺组织eNOS含量(0·3±0·1vs0·2±0·1,P<0·05)均明显升高。分流+PPG组大鼠MPAP较分流组及假手术组分别升高了15·82%和20·55%(19·5mmHg±1·7mmHgvs16·4mmHg±1·7mmHg和19·5mmHg±1·7mmHgvs15·5mmHg±1·3mmHg,P<0·05),肺组织H2S含量降低(28·8μmol/mg±2·2μmol/mgvs37·6μmol/mg±2·1μmol/mg,P<0·05),而血浆NO(27·8μmol/L±4·8μmol/Lvs23·2μmol/L±3·6μmol/L,P<0·05)、肺组织NO(46·0μmol/μg±6·0μmol/μgvs38·5μmol/μg±6·5μmol/μg,P<0·05)、NOS活性(20·9U/mg±3·9U/mgvs15·1U/mg±2·4U/mg,P<0·05)及eNOS含量均明显升高(0·4±0·1vs0·3±0·1,P<0·05)。结论内源性H2S可能通过抑制NO/NOS体系调节左向右分流大鼠肺动脉压力。

Objective To explore the impact of endogenous hydrogen sulfide （H2S） , a novel gaseous signal molecule, on the nitric oxide （NO） /nitric oxide synthase （NOS） pathway in left-to-right shunt. Methods Thirty-two male SD rats were randomly divided into 4 equal groups： shunt group undergoing abdominal aorta-inferior vena cava puncture so as to establish model of left-to-right shunt; shunt ＋ PPG group undergoing abdominal aorta-inferlor vena cava puncture so as to establish model of left-to-right shunt and then intraperitoneal injection of propagylglycine （PPG） , an inhibitor of cystathionine-γ-lyase： sham group undergoing sham operation; and sham ＋ PPG group undergoing sham operation and then intraperitoneal injection of PPG. Four weeks later, right cardiac catheterization was conducted to measure the mean pulmonary artery pressure （MPAP）. Then the rats were killed and their lung tissues and samples of plasma were collected. The contents of H2S, nitric oxide （ NO ） , and nitrogen oxide synthase （ NOS ） activity, and the content of plasma NO were calculated. Western blotting was used to detect the endothelial nitric oxide synthase （eNOS） protein in the lung tissues. The correlation of MPAP with lung H2S and NO was analyzed. Results The MPAP of the shunt group was not significantly different from that of the sham group, and the MPAP of the shunt ＋ PPG group was significantly higher then those of the shunt group and sham group by 15.82% and 20.55% respectively （ both P〈0.05）. The content of lung tissue H2S of the shunt group was 37.56±2.13 p.mol/mg, significantly higher than that of the shunt group （ 14.35±1.76, P〈0.05 ）, the content of lung tissue H2S of the shunt ＋ PPG group was 28.76±2. 24 p.mol/mg, significantly lower than that of the shunt group （P〈0.05）. The lung tissue NO content of the shunt group was 38.48 μ± 6.53 μmol/p.g, significantly higher than that of the sham group （31.78 ± 6.51μmol/μg） . The NOS activity of the shunt group was 15.12 ±2.44 U/mg protein, significantly higher than that of the sham group （ 12.00 ±1.40 U/mg protein, P〈0.05 ）. The lung eNOS content of the shunt group was significantly higher than that of the sham group （ P〈0.05 ）. The plasma NO content of the shunt group was 23.18 ± 3.56μmol/L, significantly higher than that of the sham group （ 17.94± 3.39μmol/L, P〈0.05 ）. The lung tissues NO and NOS activity, and plasma NO of the shunt ＋ PPG group were 46.04± 5.95 μmol/μg, 20.89 ± 3.94 U/mg protein, and 27.79 ± 4.82 μmol/L respectively, all significantly higher than those of the shunt group （38.48±6.53μmol/μg, 15.12 ±2.44 U/mg protein, and 23.18 ±3.56 μmol/L, all P〈0.05 ）. The eNOS content of the shunt ＋ PPG group was significantly higher than that of the shunt group （ P〈0.05 ）. The lung H2S content was negatively correlated with the MPAP and lung NO content （r=-0.705, P=0.005; andr=-0.645, P=0.013）. Condusion Endogenous H2S may play a regulatory role in the pulmonary artery pressure of left-to-fight shunt through inhibiting NO/NOS pathway.