Nitric oxide production by lymphatic endothelial cells in vitro

The present study demonstrates that confluent monolayer cultures of lymphatic endothelial cells produce and secrete NO. Immunofluorescent studies showed that eNOS activity can be stimulated with Ca ionophore to enhance the production of NO. Cells exposed to LPS and various cytokines stimulated the production of iNOS which showed the greatest increase in activity at 4 hrs and declined at 18 and 24 hrs. These studies provide evidence that, within the lymphatic vascular lumen, nitric oxide may be produced by the lymphatic endothelium which interact with various vasoactive substances to regulate lymphatic vascular tone. In addition, the production of NO by LEC may be important in the regulation of lymphatic vascular tone in order to more readily accommodate sudden fluctuations in lymph flow and pressure that normally occur during the process of lymph formation and propulsion.