The vascular occlusion methods for determination of hepatic vasoconstriction sites

我们确定三血管闭塞压（P_< ~ >），即肝动脉、门静脉和肝静脉同时闭塞时的平衡压力，是否代表离体双血管血流灌注犬肝脏的毛细血管压力（P_c）。以P_< ~ >为指标，研究门静脉或肝动脉内注射组胺（0.1 ~ 60mug）、去甲肾上腺素（NE,1 ~ 600mug）、乙酰胆碱（ACh, 0.01 ~ 10mug）或血小板活化因子（PAF,0.01 ~ 30mug）对血管阻力分布的影响。肝脏经门静脉恒流量灌注，经肝动脉恒压灌注。将P_< ~ >与传统重量法测得的P_c （P_<c, i>）进行比较。P_<to>与P_<c, i>呈较强相关性（P_<to>=-0.02+0.98 P_<c, i>; r=0.83, p=0.0018）。经比较，截距与0无显著差异，斜率与1.00无显著差异，说明…More t P_<to>准确地表示了P_c。静息时窦后血管阻力占肝血管总阻力（R_t）的54%。随着肝脏体重的增加，门脉或动脉注射组胺主要增加肝静脉阻力（R_<hv>）而不是门脉阻力。NE对门静脉和肝动脉的收缩程度大于肝静脉，R_<hv>/R_t比值明显降低。这种毛细血管前收缩伴随着肝脏重量的显著减少。相比之下，ACh和PAF在门静脉和肝静脉收缩相似，但肝脏重量没有变化。我们得出结论，P_< ~ >是对离体血流灌注犬肝脏毛细血管压力的一个很好的估计，并且静息状态下肝血管阻力位点均匀分布于窦前和窦后血管。门内或动脉内输注组胺、去甲肾上腺素、乙酰胆碱和血小板活化因子对肝血管阻力和肝体积产生了不同的改变。P_< ~ >可用于肝血流动力学的实验研究。少

We determined whether the triple vascular occlusion pressure (P_<to>), the equilibration pressure obtained when the hepatic artery, portal and hepatic veins were occluded simultaneously, represented the capillary pressure (P_c) in isolated bivascularly blood-perfused canine livers. Effects of a bolus injection of histamine (0.1-60mug), norepinephrine (NE,1-600mug), acetylcholine (ACh, 0.01-10mug) or platelet-activating factor (PAF,0.01-30mug) into the portal vein or the hepatic artery were also studied on vascular resistance distribution using P_<to> as a measure of P_c. The livers were perfused at constant flow via portal vein and at constant pressure via hepatic artery. P_<to> was compared with P_c measured using the traditional gravimetric method (P_<c, i>). P_<to> and P_<c, i> showed a strong correlation (P_<to>=-0.02+0.98 P_<c, i> ; r=0.83, p=0.0018). With comparisons, the intercept was not significantly different from zero and the slope was not different from 1.00, indicating tha … More t P_<to> accurately represented P_c. The resting postsinusoidal vascular resistance comprised of 54% of the total hepatic vascular resistance (R_t). Portal or arterial injection of histamine increased predominantly hepatic venous resistance (R_<hv>) over portal resistance with liver weight gain. NE constricted both portal vein and hepatic artery in greater magnitude than hepatic vein, as evidenced by a significant decrease in the R_<hv>/R_t ratio. This precapillary constriction was accompanied by a significant decrease in liver weight. In contrast, ACh and PAF contracted both portal and hepatic veins similarly without liver weight change. We conclude that P_<to> is an excellent estimate of the capillary pressure in isolated blood-perfused canine livers and that the hepatic vascular resistance sites in the resting states are located evenly in the pre- and postsinusoidal vessels. Intraportal or intraarterial infusion of histamine, norepinephrine acetylcholine and platelet-activating factor produced characteristically different changes in hepatic vascular resistances and hepatic volume. P_<to> could be applied in experimental research on hepatic hemodynamics. Less