一氧化氮降低肝硬化门静脉高压症血管收缩反应性的实验研究

Experimental study of nitric oxide in decreasing intestinal mesenteric arterial hypocontractility in rats with hepatic cirrhosis and portal hypertension

    摘要
  • 摘要:
    目的 探讨NO在肝硬化门静脉高压症血管收缩反应中发挥作用的机制，特别是NO与RhoA/ROCK通路间的相互作用机制。
    方法 分别测定正常大鼠(正常对照组，5只)、CCl-4诱导的肝硬化门静脉高压症大鼠(实验对照组，6只)和经LNAME处理的门静脉高压症大鼠(L-NAME处理组，6只)外周血和肠系膜动脉NO含量；利用血管灌流系统测定上述3组大鼠肠系膜微动脉对去甲肾上腺素的反应；Western blot分别检测3组大鼠肠系膜动脉NO-cGMP-PKG通路和RhoA/ROCK相关蛋白表达水平的变化。多组间均数比较采用单因素方差分析，两两比较采用LSD-t检验，肠系膜微动脉对去甲肾上腺素反应性的变化通过量效曲线表示，运用非线性回归法，计算出EC50值。
    结果 (1)正常对照组、实验对照组和L-NAME处理组大鼠平均门静脉压力分别为(6.2±0.9)mm Hg(1mm Hg=0.133 kPa)、(13.9±1.7)mm Hg和(16.6±1.3)mm Hg，3组比较，差异有统计学意义(F=94.4，P<0.05)。(2)正常对照组、实验对照组和L-NAME处理组大鼠平均血清NO浓度分别为(43±5)μmol/L、(82±16)μmol/L和(45±9)μmol/L，3组比较，差异有统计学意义(F=24.77，P<0.05)；L-NAME处理组大鼠平均NO浓度明显低于实验对照组(P<0.05)。(3)正常对照组、实验对照组和L-NAME处理组大鼠肠系膜动脉平均NO含量分别为(236±41)μmol/g、(407±82)μmol/g和(216±42)μmol/g，3组比较，差异有统计学意义(F=20.29，P<0.05)；LNAME处理组大鼠肠系膜动脉平均NO含量明显低于实验对照组(P<0.05)。(4)与实验对照组大鼠比较，L-NAME处理组大鼠的离体肠系膜微动脉对去甲肾上腺素剂量反应曲线左移，但未达到正常对照组大鼠反应曲线水平，正常对照组、实验对照组和L-NAME处理组大鼠EC50分别为6.458×10-7 mol、9.546×10-7 mol和7.494×10-7 mol，L-NAME处理组与其余两组比较，差异有统计学意义(t=2.726，3.112，P<0.05)。(5)与正常对照组比较，实验对照组大鼠肠系膜动脉eNOS蛋白和p-VASP蛋白表达水平明显增高(P<0.05)，但L-NAME处理组eNOS和pVASP蛋白表达水平显著降低，但仍高于正常对照组(P<0.05)。3组大鼠肠系膜动脉PKG-1、ROCK-1和p-moesin蛋白表达水平无明显变化(P>0.05)。(6)去甲肾上腺素刺激后，正常对照组和L-NAME处理组大鼠肠系膜动脉ROCK-1的活性显著上升，而实验对照组无变化。
    结论 CCl-4致肝硬化门静脉高压症大鼠肠系膜动脉NO含量增高，影响缩血管物质诱导ROCK激活；L-NAME降低肠系膜动脉壁内NO的含量，改善了RhoA/ROCK信号通路传递障碍，促使缩血管物质诱导ROCK激活，但不影响ROCK蛋白表达水平的变化。
     

     

    Abstract:
    Objective  To investigate the mechanisms of nitric oxide (NO) in decreasing intestinal mesenteric arterial hypocontractility in rats with hepatic cirrhosis and portal hypertension, and to analyze the interaction of NO and RhoA/ROCK pathway.
    Methods  The levels of NO in the peripheral blood and mesenteric artery of normal rats (normal control group, 5 rats), rats with portal hypertension (experimental control group, 6 rats) and rats with portal hypertension treated by L-NAME (L-NAME group, 6 rats) were detected. Mesenteric arterole contractility to norepinephrine in the 3 groups was determined using a vessel perfusion system. The expressions of proteins of NO-cGMP-PKG pathway and RhoA/ROCK pathway in the 3 groups were detected by Western blot. All data were analyzed using the analysis of variance or LSD-t test. The changes of mesenteric arteriole contractility to norepinephrine was expressed in dose-response curve, and was analyzed using the nonlinear regression method, and the EC50 value was calculated.
    Results  (1) The pressures of portal veins of the normal control group, experimental control group and L-NAME group were (6.2±0.9)mm Hg (1 mm Hg=0.133 kPa), (13.9±1.7)mm Hg and (16.6±1.3)mm Hg, respectively, with a significant difference among the 3 groups (F=94.4, P<0.05). (2) The levels of NO in the normal control group, experimental control group and L-NAME group were (43±5)μmol/L, (82±16)μmol/L and (45±9)μmol/L, respectively, with a significant difference among the 3 groups (F=24.77, P<0.05). The level of NO of the L-NAME group was significantly lower than that of the experimental control group (P<0.05). (3) The levels of NO in the mesenteric artery of the normal control group, experimental control group and L-NAME group were (236±41)μmol/g, (407±82)μmol/g and (216±42)μmol/g, respectively, with a significant difference among the 3 groups (F=20.29, P<0.05). The NO level of the L-NAME group was significantly lower than that of the experimental control group (P<0.05). (4) Compared with the experimental control group, the dose-response curve of mesenteric arterioles to norepinephrine shifted to the left, while it did not reach the level of the normal control group. The levels of EC50 of the normal control group, experimental control group and the L-NAME group were 6.458×10-7 mol, 9.546×10-7 mol and 7.494×10-7 mol, respectively. There was a significant difference in the EC50 level between the L-NAME group and the other two group (t=2.726, 3.112, P<0.05). (5) Compared with the normal control group, the protein expression levels of eNOS and pVASP of mesenteric artery of the experimental control group were significantly increased (P<0.05), while they were decreased in the L-NAME group (P<0.05). The protein expression levels of eNOS and p-VASP of mesenteric artery of the L-NAME group were significantly higher than those of the normal control group (P<0.05). There were no obvious changes of protein expression levels of PKG-1, ROCK-1 and p-moesin in the 3 groups (P>0.05). (6) The activity of ROCK-1 was significantly increased with norepinephrine stimulation in the normal control group and the L-NAME group, while no obvious changes were detected in the experimental control group.
    Conclusions  The NO expression is upregulated in mesenteric arteries in rats with hepatic cirrhosis and portal hypertension. Such changes induce ROCK activation via influencing the expression of vasoconstrictors. L-NAME can reduce the NO levels in the mesenteric arteries, which may improve RhoA/ROCK signal pathway transduction. This can help vasoconstrictors induce ROCK activation without affecting the protein expression of ROCK.

     

    • HTML全文
    • 参考文献(0)
    • 相关文章
    • 施引文献
  • 资源附件(0)

/

返回文章
返回