Abstract
The lymphatic system is a quite important part of microcirculation. The main function of the system is a drainage system of body fluid that leaks out of blood capillaries into the tissues, especially plasma protein, in the physiological condition. Also, the lymphatic system is a route of lymphocytes recirculation and metastasis of carcinoma cells. Thus to understand regulatory mechanisms of lymphatic circulation helps us investigate the function of microcirculation, immunology and oncology. In humans and animals, smooth muscles of the lymph vessels exhibit spontaneous contractile activity. Therefore the lymph vessels contribute to the active lymph transport mechanisms by the spontaneous lymphatic pump. We have demonstrated that ATP-sensitive K+ channels play crucial roles in mechanical activity of lymphatic smooth muscles and that endothelium-derived substances such as nitric oxide and prostanoids participate in the regulation of lymphatic pump activity. In addition, we have recently reported that lymphatic endothelium is a barrier against small sized-hydrophilic substances. In this symposium, we will demonstrate our current studies of the lymphatic functions indicating pump activity and permeability of lymph vessels, and then discuss the meaning and significance of lymphatic microcirculation in the cardiovascular physiology and pathophysiology. [J Physiol Sci. 2007;57 Suppl:S6]
