Document Detail

A new view of Starling's hypothesis at the microstructural level.
MedLine Citation:
PMID:  10527770     Owner:  NLM     Status:  MEDLINE    
In this paper we quantitatively investigate the hypothesis proposed by Michel (Exp. Physiol. 82, 1-30, 1997) and Weinbaum (Ann. Biomed. Eng. 26, 1-17, 1998) that the Starling forces are determined by the local difference in the hydrostatic and colloid osmotic pressure across the endothelial surface glycocalyx, which we propose is the primary molecular sieve for plasma proteins, rather than the global difference in the hydrostatic and oncotic pressure across the capillary wall between the plasma and tissue, as has been universally assumed until now. A spatially heterogeneous microstructural model is developed to explain at the cellular level why there is oncotic absorption at low capillary pressures in the short-lived transient experiments of Michel and Phillips (J. Physiol. 388, 421-435, 1987) on frog mesentery capillary, but a small positive filtration once a steady state is achieved. The new model also predicts that the local protein concentration behind the surface glycocalyx can differ greatly from the tissue protein concentration, since the convective flux of proteins through the orifice-like pores in the junction strand will greatly impede the back diffusion of the proteins into the lumen side of the cleft when the local Peclet number at the orifice is >1. The net result is that the filtration in the capillaries is far less than heretofore realized and there may be no need for venous reabsorption.
X Hu; S Weinbaum
Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Microvascular research     Volume:  58     ISSN:  0026-2862     ISO Abbreviation:  Microvasc. Res.     Publication Date:  1999 Nov 
Date Detail:
Created Date:  1999-12-10     Completed Date:  1999-12-10     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0165035     Medline TA:  Microvasc Res     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  281-304     Citation Subset:  IM; S    
Copyright Information:
Copyright 1999 Academic Press.
Department of Mechanical Engineering, The City College of The City University of New York, New York, New York 10031, USA.
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MeSH Terms
Biological Transport, Active
Blood Proteins / metabolism
Capillaries / physiology,  ultrastructure
Endothelium, Vascular / physiology*,  ultrastructure
Glycocalyx / physiology,  ultrastructure
Hydrostatic Pressure
Models, Cardiovascular*
Osmotic Pressure
Grant Support
Reg. No./Substance:
0/Blood Proteins

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