Intrinsic pump-conduit behavior of lymphangions
Intrinsic pump-conduit behavior of lymphangions
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DOI：
10.1152/ajpregu.00258.2006
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发表时间：
2007-04-01
影响因子：
2.8
通讯作者：
Stewart, Randolph H.
中科院分区：
文献类型：
--
作者：
Quick, Christopher M.;Venugopal, Arun M.;Stewart, Randolph H.
淋巴管是由瓣膜包围的淋巴管段，具有心室和动脉的特征。当主动输送淋巴液对抗压力梯度时，它们主要起泵的作用。它们也可以作为管道血管被动运输淋巴时，压力梯度。这种双重性对几种类型水肿的临床治疗有影响，因为优化淋巴流动的策略可能取决于淋巴管充当泵还是导管最有益。为了解决这种双重性，我们采用了一个简单的计算模型的收缩淋巴管，预测在正负轴向压力梯度的流量，并验证了牛肠系膜血管的体外实验的结果。该模型说明，收缩增加正常轴向压力梯度的流量。然而，在水肿、肢体抬高或外部压迫的情况下，压力梯度可能逆转，淋巴可能被动地沿着压力梯度流动。在这种情况下，瓣膜可能在整个收缩周期期间被迫打开。因此，血管作为一个管道，和收缩的影响，增加阻力，被动流，从而抑制流量，而不是促进it.This分析可能解释一个可能的生理好处，观察到的流量介导的抑制淋巴泵在高流速。
Lymphangions, segments of lymphatic vessels bounded by valves, have characteristics of both ventricles and arteries. They can act primarily like pumps when actively transporting lymph against a pressure gradient. They also can act as conduit vessels when passively transporting lymph down a pressure gradient. This duality has implications for clinical treatment of several types of edema, since the strategy to optimize lymph flow may depend on whether it is most beneficial for lymphangions to act as pumps or conduits. To address this duality, we employed a simple computational model of a contracting lymphangion, predicted the flows at both positive and negative axial pressure gradients, and validated the results with in vitro experiments on bovine mesenteric vessels. This model illustrates that contraction increases flow for normal axial pressure gradients. With edema, limb elevation, or external compression, however, the pressure gradient might reverse, and lymph may flow passively down a pressure gradient. In such cases, the valves may be forced open during the entire contraction cycle. The vessel thus acts as a conduit, and contraction has the effect of increasing resistance to passive flow, thus inhibiting flow rather than promoting it. This analysis may explain a possible physiological benefit of the observed flow-mediated inhibition of the lymphatic pump at high flow rates.