Document Detail

Rate-sensitive contractile responses of lymphatic vessels to circumferential stretch.
MedLine Citation:
PMID:  19001046     Owner:  NLM     Status:  MEDLINE    
Phasic contractile activity in rat portal vein is more sensitive to the rate of change in length than to absolute length and this response is widely assumed to be a general characteristic of myogenic behaviour for vascular smooth muscle. Previously, we found that rat lymphatic vessels exhibit phasic contractile behaviour similar to that of portal vein. In the present study, we hypothesized that lymphatic muscle would exhibit rate-sensitive contractile responses to stretch. The hypothesis was tested on rat mesenteric lymphatics (90-220 microm, i.d.) using servo-controlled wire- and pressure-myograph systems to enable ramp increases in force or pressure at different rates. Under isometric conditions in wire-myograph preparations, both the amplitude and the frequency of phasic activity were enhanced at more optimal preloads, but superimposed upon this effect were bursts of contractions that occurred only during fast preload ramps. In such cases, the ratio of contraction frequency during the ramp to that at the subsequent plateau (at optimal preload) was > 1. Further, the frequency ratio increased as a function of the preload ramp speed, consistent with a rate-sensitive mechanism. In contrast, the amplitude ratio was < 1 and declined further with higher ramp speeds. Downward preload ramps produced corresponding rate-sensitive inhibition of contraction frequency but not amplitude. Similar findings were obtained in pressurized lymphatics in response to pressure ramps and steps. Our results suggest that lymphatics are sensitive to the rate of change in preload/pressure in a way that is different from portal vein, possibly because the pacemaker for generating electrical activity is rate sensitive but lymphatic muscle is not. The behaviour may be widely present in collecting lymphatic vessels and is probably an important mechanism for rapid adaptation of the lymphatic pump to local vascular occlusion.
Michael J Davis; Ann M Davis; Megan M Lane; Christine W Ku; Anatoliy A Gashev
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2008-11-10
Journal Detail:
Title:  The Journal of physiology     Volume:  587     ISSN:  1469-7793     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  2009 Jan 
Date Detail:
Created Date:  2009-01-02     Completed Date:  2009-03-18     Revised Date:  2013-06-04    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  165-82     Citation Subset:  IM    
Department of Medical Pharmacology and Physiology University of Missouri School of Medicine 1 Hospital Dr., Rm. M451 Columbia, MO 65212, USA.
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MeSH Terms
Isometric Contraction / physiology
Lymphatic Vessels / physiology*
Muscle, Smooth / physiology
Organ Specificity
Portal Vein / physiology
Rats, Sprague-Dawley
Stress, Mechanical
Grant Support

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