The vascular occlusion methods for determination of hepatic vasoconstriction sites

我们测定了肝动脉、门静脉和肝静脉同时阻断时的三血管阻断压(P_t；to_gt；)是否代表双血管灌流犬肝脏的毛细血管压(P_C)。将组胺(0.1-60µg)、去甲肾上腺素(NE，1-600µg)、乙酰胆碱(ACh，0.01-10µg)或血小板活化因子(PAF，0.01-30µg)团注入门静脉或肝动脉，以P_c为指标，研究了组胺(0.1-60µg)、去甲肾上腺素(NE，1-600µg)、乙酰胆碱(ACh，0.01-10µg)或血小板活化因子(PAF，0.01-30µg)对血管阻力的影响。与传统重量法(P&lt；c，I&gt；)测得的P_c进行比较。P&lt；与P&lt；c，I&gt；呈显著正相关(P=-0.02+0.98P&lt；c，r=0.83，p=0.0018)。通过比较，截距与零无显著差异，斜率与1.00无显著差异，表明…静息状态下肝窦后血管阻力占总肝血管阻力的54%。随着肝脏重量增加，门静脉或动脉注射组胺主要增加肝静脉阻力(R&lt；hv&gt；)，超过门静脉阻力。NE对门静脉和肝动脉的收缩程度均大于肝静脉，表现为R&lt；hv&gt；/Rt比值显著降低。这种毛细血管前收缩伴随着肝脏重量的显著下降。相反，ACh和PAF对门静脉和肝静脉的收缩相似，而肝脏重量没有变化。我们的结论是，P&lt；to&gt；是一个很好的估测离体血灌流犬肝脏毛细血管压力的方法，而且静息状态下的肝血管阻力部位均匀地分布在肝窦前和肝窦后的血管中。门脉内或动脉内注入组胺、去甲肾上腺素、乙酰胆碱和血小板激活因子在肝血管阻力和肝体积中产生不同的特征变化。可用于肝血流动力学的实验研究。较少

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