The vascular occlusion methods for determination of hepatic vasoconstriction sites

在离体双血管灌注犬肝脏中，我们测定了三支血管阻断压（P_c）是否<to>代表毛细血管压力（P_c）。三支血管阻断压是指肝动脉、门静脉和肝静脉同时阻断时的平衡压。本文还研究了门静脉或肝动脉注射组胺（0.1- 60 μ g）、去甲肾上腺素（NE，1- 600 μ g）、乙酰胆碱（ACh，0.01- 10 μ g）或血小板活化因子（PAF，0.01 - 30 μ g）对血管阻力分布的影响<to>。采用门静脉恒流灌注法和肝动脉恒压灌注法。并<to>与传统重量法测得的P_c（P_&lt;c，i&gt;）进行比较。P_<to>（1）与P_（c，i）呈强相关（P_<to>=-0.02 +0.98P_（c，i）; r=0.83，p=0.0018）。通过比较，截距与0无显著差异，斜率与1.00无显著差异，表明 关于我们 t P_<to>准确地表示P_c。静息状态下肝窦后血管阻力占总肝血管阻力（Rt）的54%。门脉或动脉注射组胺后，随着肝脏重量的增加，肝静脉阻力（R_）显著增加<hv>，超过门脉阻力。NE对门静脉和肝动脉的收缩程度大于肝静脉，表现为R_<hv>/R_t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降低。相比之下，ACh和PAF收缩门静脉和肝静脉相似，肝脏重量无变化。我们的结论是，P_<to>是一个很好的估计毛细血管压力在离体血液灌注犬肝脏和肝脏血管阻力网站在静息状态下均匀地位于前和后窦血管。门脉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可引起肝血管阻力和肝体积的特征性不同变化。P_1<to>可用于肝脏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