title: Current topics of physiology and pharmacology in the lymphatic system.
abstract: We have reviewed physiological significance of rhythmical spontaneous contractions of collecting lymph vessels, which play a pivotal role in lymph transport and seem to control lymph formation through changing the pacemaker sites of the rhythmic contractions and contractile patterns of the lymphangions. A characteristic feature that the rhythmic pump activity works in vivo physiologically under the specific environment of lower oxygen tension in lymph (25-40 mm Hg) has been evaluated. With the characteristic feature, generation of endogenous nitric oxide (NO) from lymphatic endothelial cells and/or activation of ATP-sensitive potassium channels (K(ATP)) are reviewed to play crucial roles in the regulation of lymph transport at physiological or pathophysiological conditions. Chemical substances released from malignant tumor cells and tumor-derived parathyroid hormone-related peptide (PTHr-P) are also shown to cause a significant reduction of lymphatic pump activity through generation of endogenous NO and activation of K(ATP) channels. Finally, we have discussed physiological significance and roles of the lower oxygen tension in lymph, generation of endogenous NO, and activation of K(ATP) in lymph formation, lymph transport, and the functions of lymph nodes.
authors.affiliation: Department of Physiology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan. ohhashi@sch.md.shinshu-u.ac.jp
authors.forename: Toshio
authors.initials: T
authors.lastname: Ohhashi
authors.forename: Risuke
authors.initials: R
authors.lastname: Mizuno
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Ikomi
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Kawai
mesh_terms: D000255:Adenosine Triphosphate / Q000502:physiology; D000818:Animals; D042783:Endothelial Cells / Q000378:metabolism; D008207:Lymphatic Metastasis; D008208:Lymphatic System / Q000201:enzymology / Q000378:metabolism / Q000502:physiology*; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D009369:Neoplasms / Q000378:metabolism / Q000473:pathology; D009569:Nitric Oxide / Q000502:physiology; D010100:Oxygen / Q000502:physiology; D010313:Partial Pressure; D015221:Potassium Channels / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D015221:Potassium Channels; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D000255:Adenosine Triphosphate; D010100:Oxygen