Myogenic constriction and dilation of isolated lymphatic vessels

• Published in: American journal of physiology. Heart and circulatory physiology 2009-02, Vol.296 (2), p.H293-H302
• Main Authors: Davis, Michael J, Davis, Ann M, Ku, Christine W, Gashev, Anatoliy A
• Format: Article
• Language: English
• Subjects: Animals; Blood pressure; Constriction, Pathologic; Dilatation, Pathologic; In Vitro Techniques; Inflammation Mediators - metabolism; Lymphatic system; Lymphatic Vessels - metabolism; Lymphatic Vessels - pathology; Male; Mesentery; Muscle Contraction; Muscle Relaxation; Pressure; Rats; Rats, Sprague-Dawley; Rodents; Studies; Substance P - metabolism; Time Factors
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.01040.2008

1 Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri; and 2 Division of Lymphatic Biology, Department of Systems Biology and Translational Medicine, Cardiovascular Research Institute, Texas A & M Health Science Center, Temple, Texas Submitted 29 September 2008 ; accepted in final form 19 November 2008 We tested the hypothesis that lymphatics would exhibit myogenic constrictions and dilations to intraluminal pressure changes. Collecting lymphatic vessels were isolated from rat mesentery, cannulated, and pressurized for in vitro study. The lymphatic diameter responses to controlled intraluminal pressure steps of different magnitudes were tested in the absence and presence of the inflammatory mediator substance P, which is known to enhance lymphatic contractility. Myogenic constriction, defined as a time-dependent decrease in end-diastolic diameter over a 1- to 2-min period following pressure elevation (after initial distension), was observed in the majority of rat mesenteric lymphatic vessels in vitro and occurred over a relatively wide pressure range (1–15 cmH 2 O). Myogenic dilation, a time-dependent rise in end-diastolic diameter following pressure reduction, was observed in over half the vessels equilibrated at a low baseline pressure. Myogenic constrictions were independent of the cardiac-like and time-dependent compensatory decline in end-systolic diameter and increase in amplitude observed in almost all vessels following pressure elevation. Substance P increased the percentage of vessels exhibiting myogenic constriction, the magnitude and rate of constriction, and the pressure range over which constriction occurred. Our results demonstrate that myogenic responses occur in collecting lymphatic vessels and suggest that the response may aid in preventing vessel overdistension during inflammation/edema. lymphatic contraction; lymphatic contractility; substance P; inflammation Address for reprint requests and other correspondence: M. J. Davis, Dept. of Medical Pharmacology & Physiology, Univ. of Missouri School of Medicine, 1 Hospital Dr., Rm. M451, Columbia, MO 65212 (e-mail: davismj{at}health.missouri.edu )