Document Detail

Constriction of isolated collecting lymphatic vessels in response to acute increases in downstream pressure.
MedLine Citation:
PMID:  23045335     Owner:  NLM     Status:  MEDLINE    
Collecting lymphatic vessels generate pressure to transport lymph downstream to the subclavian vein against a significant pressure head. To investigate their response to elevated downstream pressure, collecting lymphatic vessels containing one valve (incomplete lymphangion) or two valves (complete lymphangion) were isolated from the rat mesentery and tied to glass cannulae capable of independent pressure control. Downstream pressure was selectively raised to various levels, either stepwise or ramp-wise, while keeping upstream pressure constant. Diameter and valve positions were tracked under video microscopy, while intralymphangion pressure was measured concurrently with a servo-null micropipette. Surprisingly, a potent lymphatic constriction occurred in response to the downstream pressure gradient due to (1) a pressure-dependent myogenic constriction and (2) a frequency-dependent decrease in diastolic diameter. The myogenic index of the lymphatic constriction (-3.3 ± 0.6, in mmHg) was greater than that of arterioles or collecting lymphatic vessels exposed to uniform increases in pressure (i.e. upstream and downstream pressures raised together). Additionally, the constriction was transmitted to the upstream lymphatic vessel segment even though it was protected from changes in pressure by a closed intraluminal valve; the conducted constriction was blocked by loading only the pressurized half of the vessel with either ML-7 (0.5 mm) to block contraction, or cromakalim (3 μm) to hyperpolarize the downstream muscle layer. Finally, we provide evidence that the lymphatic constriction is important to maintain normal intraluminal valve closure during each contraction cycle in the face of an adverse pressure gradient, which probably protects the lymphatic capillaries from lymph backflow.
Joshua P Scallan; John H Wolpers; Michael J Davis
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2012-10-08
Journal Detail:
Title:  The Journal of physiology     Volume:  591     ISSN:  1469-7793     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-01-16     Completed Date:  2013-06-21     Revised Date:  2014-01-24    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  443-59     Citation Subset:  IM    
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MeSH Terms
Arterioles / physiology
Cromakalim / pharmacology
Lymph / physiology*
Lymphatic Vessels / anatomy & histology,  physiology*
Muscle Contraction / drug effects,  physiology
Muscle, Smooth / physiology*
Rats, Sprague-Dawley
Grant Support
Reg. No./Substance:
Comment In:
J Physiol. 2013 Jan 15;591(Pt 2):391-2   [PMID:  23322290 ]

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