Department of Bioengineering, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom.
Department of Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO 65212, USA.
Sci Rep. 2017 Sep 21;7(1):12080. doi: 10.1038/s41598-017-11599-x.
Many tissues exhibit subatmospheric interstitial pressures under normal physiologic conditions. The mechanisms by which the lymphatic system extracts fluid from these tissues against the overall pressure gradient are unknown. We address this important physiologic issue by combining experimental measurements of contractile function and pressure generation with a previously validated mathematical model. We provide definitive evidence for the existence of 'suction pressure' in collecting lymphatic vessels, which manifests as a transient drop in pressure downstream of the inlet valve following contraction. This suction opens the inlet valve and is required for filling in the presence of low upstream pressure. Positive transmural pressure is required for this suction, providing the energy required to reopen the vessel. Alternatively, external vessel tethering can serve the same purpose when the transmural pressure is negative. Suction is transmitted upstream, allowing fluid to be drawn in through initial lymphatics. Because suction plays a major role in fluid entry to the lymphatics and is affected by interstitial pressure, our results introduce the phenomenon as another important factor to consider in the study of lymphoedema and its treatment.
许多组织在正常生理条件下表现出亚大气压的间质压力。淋巴系统在整体压力梯度下从这些组织中提取液体的机制尚不清楚。我们通过将收缩功能和压力产生的实验测量与先前经过验证的数学模型相结合来解决这个重要的生理问题。我们为收集淋巴管中存在“抽吸压力”提供了明确的证据，这表现为收缩后入口阀下游的压力短暂下降。这种抽吸会打开入口阀，并在上游压力较低时填充时需要。这种抽吸需要正壁压，为重新打开血管提供所需的能量。或者，当壁压为负时，外部血管束缚也可以达到同样的效果。抽吸会向上游传递，允许流体通过初始淋巴管进入。由于抽吸在流体进入淋巴管中起着重要作用，并且受到间质压力的影响，因此我们的结果表明，抽吸是研究淋巴水肿及其治疗时需要考虑的另一个重要因素。
