Document Detail


First-order approximation for the pressure-flow relationship of spontaneously contracting lymphangions.
MedLine Citation:
PMID:  18326809     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
To return lymph to the great veins of the neck, it must be actively pumped against a pressure gradient. Mean lymph flow in a portion of a lymphatic network has been characterized by an empirical relationship (P(in) - P(out) = -P(p) + R(L)Q(L)), where P(in) - P(out) is the axial pressure gradient and Q(L) is mean lymph flow. R(L) and P(p) are empirical parameters characterizing the effective lymphatic resistance and pump pressure, respectively. The relation of these global empirical parameters to the properties of lymphangions, the segments of a lymphatic vessel bounded by valves, has been problematic. Lymphangions have a structure like blood vessels but cyclically contract like cardiac ventricles; they are characterized by a contraction frequency (f) and the slopes of the end-diastolic pressure-volume relationship [minimum value of resulting elastance (E(min))] and end-systolic pressure-volume relationship [maximum value of resulting elastance (E(max))]. Poiseuille's law provides a first-order approximation relating the pressure-flow relationship to the fundamental properties of a blood vessel. No analogous formula exists for a pumping lymphangion. We therefore derived an algebraic formula predicting lymphangion flow from fundamental physical principles and known lymphangion properties. Quantitative analysis revealed that lymph inertia and resistance to lymph flow are negligible and that lymphangions act like a series of interconnected ventricles. For a single lymphangion, P(p) = P(in) (E(max) - E(min))/E(min) and R(L) = E(max)/f. The formula was tested against a validated, realistic mathematical model of a lymphangion and found to be accurate. Predicted flows were within the range of flows measured in vitro. The present work therefore provides a general solution that makes it possible to relate fundamental lymphangion properties to lymphatic system function.
Authors:
Christopher M Quick; Arun M Venugopal; Ranjeet M Dongaonkar; Glen A Laine; Randolph H Stewart
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.     Date:  2008-03-07
Journal Detail:
Title:  American journal of physiology. Heart and circulatory physiology     Volume:  294     ISSN:  0363-6135     ISO Abbreviation:  Am. J. Physiol. Heart Circ. Physiol.     Publication Date:  2008 May 
Date Detail:
Created Date:  2008-05-07     Completed Date:  2008-06-12     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100901228     Medline TA:  Am J Physiol Heart Circ Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  H2144-9     Citation Subset:  IM    
Affiliation:
Michael E. DeBakey Institute, Texas A&M University, College Station, TX 77843-4466, USA. cquick@tamu.edu
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MeSH Terms
Descriptor/Qualifier:
Animals
Cattle
Elasticity
Lymph / physiology*
Lymphatic Vessels / anatomy & histology,  physiology*
Models, Biological*
Muscle Contraction*
Muscle, Smooth / physiology*
Perfusion
Pressure
Reproducibility of Results
Rheology
Viscosity
Grant Support
ID/Acronym/Agency:
CDC-620069//PHS HHS; CDC-623086//PHS HHS; K25 HL 070605/HL/NHLBI NIH HHS

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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