Nonlinear resistances in hepatic microcirculation.
Nonlinear resistances in hepatic microcirculation.
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肝脏微循环的非线性阻力。
DOI：
10.1152/ajpheart.1995.269.6.h1922
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Rothe,CF
中科院分区：
文献类型：
--
作者：
Maass-Moreno,R;Rothe,CF
肝脏提供了一个可用于动员大量血液的储库，但如果下游（流出）压力变化低于一定幅度（破裂压力）不会改变上游压力，则血量重新分配可能会受到限制。对于大于破坏压力的下游压力，上游压力成比例地变化。我们测试了这样的假设：从腹部腔静脉到肝脏微循环以及从肝脏微循环到门静脉可以发现这种非线性压力传递模式。使用零伺服微移液器技术，我们测量了兔子肝脏表面的微血管压力。在 30 次测量中的 16 次中，通过部分阻塞尾部胸腔静脉来增加肝脏流出处的压力，仅在腹部腔静脉压力超过 2.85 +/- 0.92 mmHg 的破裂压力后才导致肝小静脉压力增加。在 31 次测量中的 13 次中，直到肝小静脉压力超过 3.36 +/- 0.54 mmHg 的破裂压力时，门静脉压力才发生变化。正弦曲线和门静脉也获得了类似的行为和值。当存在时，上游-下游压力图中的急剧拐点表明这可能是由 Starling 电阻器型机制引起的。当不存在破裂时，下游压力可能大于破裂压力。我们得出结论，具有非线性特征的显着肝阻力存在于中央小静脉、正弦曲线和门静脉的上游和下游。
The liver provides a reservoir available for mobilizing large amounts of blood, but if a change in downstream (outflow) pressure below a certain magnitude (break pressure) does not change upstream pressures, blood volume redistribution may be limited. For downstream pressures larger than the break pressure, the upstream pressures change proportionately. We tested the hypothesis that this nonlinear mode of pressure transmission could be found from the abdominal vena cava to the hepatic microcirculation and from the hepatic microcirculation to the portal vein. Using a servo-null micropipette technique, we measured microvascular pressures at the liver surface of rabbits. In 16 of 30 measurements, increasing the pressure at the liver outflow, by partially occluding the caudal thoracic vena cava, caused an increase in hepatic venular pressure only after the abdominal vena caval pressure exceeded a break pressure of 2.85 +/- 0.92 mmHg. In 13 of 31 measurements, portal venous pressure was not changed until the hepatic venular pressure exceeded a break pressure of 3.36 +/- 0.54 mmHg. Similar behavior and values were obtained for sinusoids and portal venules. When present, the sharp inflection in the upstream-downstream pressure plots suggests that this may be caused by a Starling resistor-type mechanism. When the break was absent, the downstream pressure may have been larger than the break pressure. We conclude that significant hepatic resistances with nonlinear characteristics exist upstream and downstream to the central venules, sinusoids, and portal venules.