title: Modulation of lymphatic smooth muscle contractile responses by the endothelium.
abstract: The endothelium regulates smooth muscle tone in blood vessels through the release of endothelium-deprived relaxing factor (EDRF). We hypothesized that the lymphatics possess endothelium-dependent relaxant properties analogous to those in blood vessels. Fresh porcine tracheobronchial lymphatic vessel rings were mounted in organ baths and connected to force-displacement transducers. Rings were submaximally precontracted with 10(-5) M histamine and exposed to cumulative addition of acetylcholine (ACH; 10(-7)-3 x 10(-4) M) or bradykinin (BRD; 10(-8)-3 x 10(-6) M), both of which are known to promote release of EDRF. ACH caused concentration-dependent relaxation (maximum effect = -2.3 +/- 2.6% of initial histamine-induced active tension), while a similar but less pronounced effect was seen with BRD (39.6 +/- 5.4%). The relaxant effects of ACH and BRD were inhibited by collagenase pretreatment and mechanical endothelial denudation. The results confirm our hypothesis that lymphatic vessels possess endothelium-dependent relaxant properties and suggest that lymph vessels can regulate lymph flow through processes similar to those found in blood vessels.
authors.affiliation: Department of Surgery, University of Chicago, Illinois 60637.
authors.forename: M K
authors.initials: MK
authors.lastname: Ferguson
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D001980:Bronchi / Q000187:drug effects; D004727:Endothelium / Q000502:physiology; D005260:Female; D006652:Histological Techniques; D008208:Lymphatic System / Q000187:drug effects / Q000502:physiology*; D008297:Male; D003012:Microbial Collagenase / Q000494:pharmacology; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D013552:Swine; D014132:Trachea / Q000187:drug effects
chemical_list: D003012:Microbial Collagenase; D000109:Acetylcholine; D001920:Bradykinin