血小板活性因子及其拮抗剂对大鼠肝硬化门脉高压的影响

目的探讨肝硬化时肝脏和血循环中血小板活性因子(PAF)的变化以及其对门脉高压的影响。方法CCl4腹腔注射8周(0·15ml/kg,2次/周)诱导大鼠肝硬化,快速3H-PAF液闪检测肝及循环中PAF水平;受体饱和结合实验分析肝组织PAF结合能力;监测外源性PAF及其拮抗剂BN52021对门脉压和系统动脉压的影响。结果与对照组相比,肝硬化时肝内PAF、肝脏输出PAF及肝内生PAF水平明显升高,分别4·0ng/g±0·4ng/gvs2·7ng/g±0·5ng/g(P<0·01)、6·3ng/ml±0·6ng/mlvs3·4ng/ml±0·6ng/ml(P<0·01)、1·0ng/ml±0·6ng/mlvs-0·3ng/ml±0·5ng/ml(P<0·01);肝组织PAF结合能力Bmax明显升高(2·8±0·21)fmol/μg膜蛋白vs(0·9±0·06)fmol/μg膜蛋白,P<0·01,而受体亲和力Kd差异无统计学意义(8·0nmol/L±1·3nmol/Lvs5·8nmol/L±1·0nmol/L,P>0·05)。肝硬化组基础门脉压升高(12·2mmHg±0·7mmHgvs5·3mmHg±0·6mmHg,P<0·01),系统动脉压降低(82mmHg±10mmHgvs114mmHg±9mmHg,P<0·01)。门脉注入PAF(1μg/kg)后,肝硬化组门脉压提高了32%(12·1mmHg±0·6mmHgvs16·0mmHg±0·7mmHg,P<0·01),升高幅度约为对照组的227%(4·1mmHg±1·0mmHgvs1·8mmHg±0·3mmHg,P<0·01),而系统动脉压在两组均下降(肝硬化组由82mmHg±10mmHg降至48mmHg±4mmHg,P<0·01;对照组由114mmHg±9mmHg降至52mmHg±4mmHg,P<0·01)。门脉注入BN52021(5mg/kg),肝硬化组门脉压降低了16%(14·6mmHg±1·6mmHgvs12·3mmHg±0·8mmHg,P<0·05),而系统动脉压在肝硬化组和对照组均无明显变化(P>0·05)。结论肝硬化时肝脏合成PAF明显增加是循环血PAF升高的重要来源,并上调节肝的血流动力学影响门脉高压形成,其作用可被其拮抗剂BN52021部分逆转。

Influence of platelet activating factor and its antagonist on portal hypertension associated with liver cirrhosis: an experiment with rats

OBJECTIVE: To investigate the influence of platelet activating factor (PAF) and its antagonist BN52021 on portal hypertension associated with liver cirrhosis. METHODS: Ten SD rats were injected intraperitoneally with carbon tetrachloride to establish a liver cirrhosis model and 10 rats were injected with olive oil as controls. The concentrations of PAF in the blood and liver was examined by rapid (3)H-PAF scintillation proximity assay and the hepatic PAF binding capacity was examined by receptor saturation binding technique. The pressure of portal vein and pressure of femoral artery were measured by intubation method. BN52021 was infused into the portal vein to observe its influence on the blood pressure. RESULTS: The hepatic PAF levels of the cirrhotic rats was 4.0 ng/g +/- 0.4 ng/g, significantly higher than that of the control rats (2.7 ng/g +/- 0.5 ng/g, P < 0.01). The hepatic efflux PAF level of the cirrhotic rats was 6.3 ng/g +/- 0.6 ng/g, significantly higher than that of the control rats (3.4 ng/g +/- 0.6 ng/g, P < 0.01). The hepatic output PAF levels of the cirrhotic rats was 1.0 ng/g +/- 0.6 ng/g, significantly lower than that of the control rats (0.3 ng/g +/- 0.5 ng/g, P < 0.01). The maximum PAF binding capacity of the cirrhotic rats was 2.8 +/- 0.21 fmol/microg protein, significantly higher than that of the control rats (0.9 +/- 0.06 fmol/microg protein, P < 0.01). However, the receptor affinity was not significantly different between these 2 groups. The portal pressure of the cirrhotic rats was 12.2 mm Hg +/- 0.7 mm Hg, significantly higher than that of the control rats (5.3 mm Hg +/- 0.6 mm Hg, P < 0.01). The femoral arterial pressure of the cirrhotic rats was 82 mm Hg +/- 10 mm Hg, significantly lower than that of the control rats (114 mm Hg +/- 9 mm Hg, P < 0.01). Infusion of PAF via the portal vein increased the portal pressure from 12.1 mm Hg +/- 0.6 mm Hg with an increase of 32% (P < 0.01) in the cirrhotic rats, and from 7.7 mm Hg +/- 0.8 mm Hg with an increase of 23%. The PAF response of the cirrhotic rats was 4.1 mm Hg +/- 1.0 mm Hg (227%), significantly higher than that of the control rats (1.8 mm Hg +/- 0.3 mm Hg, P < 0.01). The femoral artery pressure decreased from 82 mm Hg +/- 10 mm Hg to 48 mm Hg +/- 4 mm Hg (P < 0.01) in the cirrhotic rats, and from 114 mm Hg +/- 9 mm Hg to 52 mm Hg +/- 4 mm Hg (P < 0.01). After portal infusion of BN52021 the portal pressure decreased from 14.6 mm Hg +/- 1.6 mm Hg to 12.3 mm Hg +/- 0.8 mm Hg (P < 0.05) with a decrease of 16%, however, did not significantly influenced the femoral arterial pressure in the cirrhotic rats, and did not significantly influenced the portal pressure and femoral arterial pressure in the control rats. CONCLUSION: The increased hepatic PAF synthesis in cirrhotic is the major source of elevated circulating PAF It upregulates the hepatic hemodynamics that contributes to portal hypertension. The increased portal pressure by endogenous PAF can be decreased to a certain extent by BN52021 which may be used in treatment of portal hypertension.