In Situ Lymph Dynamic Characterization through Lymph Nodes in Rabbit Hind Leg: Special Reference to Nodal Inflammation

In some lymph nodes, water and water-soluble substances of smaller molecular weight are known to be absorbed into blood vessels, and consequently the protein concentration of lymph within the nodes increases. In this study, we examined pressure-flow relationships of lymph nodes in situ and exchange properties of water and water-soluble substances through the nodes with special reference to inflamed lymph nodes. A lymph perfusion model through the lymph node in situ was constructed by cannulating one of the afferent lymphatics and an efferent lymphatic. Increasing infusion pressure (0 to 150 cmH2O) or decreasing outflow pressure (10 to −5 cmH2O) in the model caused a significant increase of the lymph outflow rate through the node. This rate was also increased significantly with increases in both intranodal venous pressure (range: control, 20, 30, and 40 mmHg) and prenodal lymph albumin concentration (range: 0%, 2.6%, and 10%). When formyl-Met-Leu-Phe-OH (fMLP)–mediated acute inflammation was produced in the lymph nodes, the lymph outflow rate through the node was significantly decreased. These results indicate that colloid osmotic pressure and hydrostatic pressure within the lymph node may play important roles in the transport of water and water-soluble substances through the node. Acute fMLP-mediated inflammation of lymph nodes also produced a significant decrease of the lymph flow rate through lymph nodes.