title: Heterogeneity of tracheobronchial lymphatic smooth muscle responses to histamine and 5-hydroxytryptamine.
abstract: We assessed the responsiveness of tracheobronchial lymphatic smooth muscle to mediators of inflammation to determine whether homogeneous responses to histamine and 5-hydroxytryptamine (5-HT) are demonstrated among species typically used in studies of lymph vessels. Fresh porcine and bovine tracheobronchial lymph vessels were suspended from force-displacement transducers in baths containing oxygenated Krebs solution. Concentration-response curves were generated by cumulative addition of histamine (10(-7) to 10(-3) M) or 5-HT (10(-7) to 3 x 10(-4) M). Active tension (AT) was expressed in milligrams and as a percentage of initial vessel ring response to 65mM KCl. Histamine elicited concentration-dependent contraction, yielding maximum AT in porcine rings of 1116 +/- 127 mg (n = 39; 129.1 +/- 10.5% of KCl response) and in bovine rings of 733 +/- 106 mg (n = 20; 65.8 +/- 12.9%; P = 0.0005 for percent responses). PD2 values (negative log10 of the concentration at half-maximum effect) were 4.49 +/- 0.08 and 4.82 +/- 0.08; (P = 0.0034). 5-HT elicited concentration-dependent contraction, yielding maximum AT of 560 +/- 50 mg in porcine rings (n = 15; 97.2 +/- 9.7%) and 2892 +/- 454 mg in bovine rings (n = 27; 159.0 +/- 29%; P < 0.0001 for percent responses). PD2 values were 6.25 +/- 0.05 and 5.28 +/- 0.04 (P < 0.0001). The data demonstrate a role for inflammatory mediators in the modulation of tracheobronchial lymphatic smooth muscle tone that is species- and mediator-specific, and support the potential for paracrine regulation of tracheobronchial lymph flow.
authors.affiliation: Department of Surgery, University of Chicago, Illinois.
authors.forename: M K
authors.initials: MK
authors.lastname: Ferguson
authors.forename: U E
authors.initials: UE
authors.lastname: Williams
authors.forename: A R
authors.initials: AR
authors.lastname: Leff
authors.forename: R W
authors.initials: RW
authors.lastname: Mitchell
mesh_terms: D000818:Animals; D001980:Bronchi / Q000187:drug effects*; D002417:Cattle; D005260:Female; D006632:Histamine / Q000494:pharmacology*; D066298:In Vitro Techniques; D008208:Lymphatic System / Q000187:drug effects*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D012701:Serotonin / Q000494:pharmacology*; D013552:Swine; D014132:Trachea / Q000187:drug effects*
chemical_list: D012701:Serotonin; D006632:Histamine