Developmental study for hybrid artificial lymph vessels:its potential role of permeability

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One of the major functions of the lymphatic system is to return plasma proteins from the tissue space to the blood stream. In addition, the lymphatic system has a unique mechanism that lymphatics and lymph nodes could modulate lymph contents during transport of lymph. These mechanisms are considered to be important for understanding lymphatic physiology as well as the pathophysiology associated with lymphatic disorders. In this project, for development of hybrid artificial lymph vessels, we have studied the functions of endothelial cells and smooth muscle cells of the lymph vessels focusing on the permeability. NaF1 and FITC-dextran 4400 (4kD) in the intraluminal space of isolated rat lymph vessels penetrated the wall of lymph vessels. FITC-dextran 12000 (12kD) in the intraluminal space of isolated rat lymph vessels slightly passed through the lymphatic wall, while FITC-dextran 71200 (70kD) did not penetrate the wall. After administration of CHAPS or TNF≪ into the lymph vessels, the net flux of FITC-dextran 4400 and 12000, but not 71200, augmented. TNFα caused a re-arrangement of F-actin in cultured lymphatic endothelial cells. These results suggest that small molecular hydrophilic substances (〓 4400) are permeable from the intraluminal to extrahiminal space of isolated lymph vessels and that the endothelial cell surface structure may play a barrier role in the effective permeability of large molecular hydrophilic substances (4400 to 12000) through the wall of the lymph vessels. Glucose derived from intracellular glycogen and/or through GLUT/SGLT in lymphatic smooth muscles contributes to the regulation of pump activity of isolated rat thoracic ducts, and that mitochondrial K_<ATP> in the cells may partially serve as a modulator of the mechanical functions associated with mitochondrial Ca^<2+> uptake. In this project we demonstrated important issues regarding "Developmental study for hybrid artificial lymph vessels: its potential role of permeability".