Dipartimento di Scienze Biomediche Sperimentali e Cliniche, Università degli Studi dell'Insubria, Via J.H. Dunant 5, 21100 Varese, Italy.
J Physiol. 2011 Jun 15;589(Pt 12):2927-34. doi: 10.1113/jphysiol.2011.206672. Epub 2011 Apr 11.
Lymph formation is driven by hydraulic pressure gradients developing between the interstitial tissue and the lumen of initial lymphatics. While in vessels equipped with lymphatic smooth muscle cells these gradients are determined by well-synchronized spontaneous contractions of vessel segments, initial lymphatics devoid of smooth muscles rely on tissue motion to form lymph and propel it along the network. Lymphatics supplying highly moving tissues, such as skeletal muscle, diaphragm or thoracic tissues, undergo cyclic compression and expansion of their lumen imposed by local stresses arising in the tissue as a consequence of cardiac and respiratory activities. Active muscle contraction and not passive tissue displacement is required to support an efficient lymphatic drainage, as suggested by the fact that the respiratory activity promotes lymph formation during spontaneous, but not mechanical ventilation. The mechanical properties of the lymphatic wall and of the surrounding tissue also play an important role in lymphatic function. Modelling of stress distribution in the lymphatic wall suggests that compliant vessels behave as reservoirs accommodating absorbed interstitial fluid, while lymphatics with stiffer walls, taking advantage of a more efficient transmission of tissue stresses to the lymphatic lumen, propel fluid through the lumen of the lymphatic circuit.
淋巴液的形成是由间质组织和初始淋巴管管腔之间的液压梯度驱动的。虽然在配备有淋巴管平滑肌细胞的血管中，这些梯度是由血管段的同步自发收缩决定的，但没有平滑肌的初始淋巴管依赖于组织运动来形成淋巴液并沿着网络推动它。供应高度运动组织（如骨骼肌、膈肌或胸组织）的淋巴管，其管腔会经历周期性的压缩和扩张，这是由于心脏和呼吸活动引起的组织内产生的局部应力造成的。主动肌肉收缩而不是被动组织移位对于支持有效的淋巴引流是必需的，这一事实表明，呼吸活动在自发呼吸而非机械通气时促进了淋巴液的形成。淋巴管壁和周围组织的力学特性也在淋巴功能中起着重要作用。对淋巴管壁的应力分布进行建模表明，顺应性血管充当容纳吸收的间质液的储液器，而具有更硬壁的淋巴管则利用更有效地将组织应力传递到淋巴管腔，推动液体通过淋巴管回路的管腔。
