Transport models for the interendothelial cleft.
Item
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Title
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Transport models for the interendothelial cleft.
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Identifier
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AAI9605593
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identifier
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9605593
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Creator
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Fu, Bing-Mei.
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Contributor
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Advisers: Sheldon Weinbaum | Fitz-Roy E. Curry
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Date
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1995
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Language
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English
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Publisher
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City University of New York.
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Subject
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Engineering, Biomedical | Biology, Animal Physiology
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Abstract
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Vascular endothelium is the principal barrier to, and regulator of, material exchange between circulating blood and the body tissues. The ultrastructural pathways and mechanisms whereby endothelial cells and the clefts between the cells modulate capillary permeability to water and solutes have been a central unsolved question in microvessel transport since the early 1950's. Three new theoretical models have been developed in this research to examine the role of the detailed structure of the intercellular cleft and its components in the regulation of capillary permeabilities. These new approaches have resulted in a major revision of current ideas about the pathways for water and solutes through the junction strand and the structures that determine the molecular filter.;The combined junction-orifice-fiber entrance layer model proposed in this dissertation predicts that for measured hydraulic conductivity to be achieved the fiber layer must be confined to a relatively narrow region at the entrance to the cleft where it serves as the primary molecular filter provided the fiber matrix forms an ordered array. This model also provides an excellent fit for the hydraulic conductivity and the diffusive permeability data for solutes of size ranging from potassium to albumin for frog mesenteric capillary provided the junction strand contains at least two types of pores, infrequent 20 x 150 nm large orifice breaks and a continuous {dollar}\sim{dollar}2 nm narrow slit or closely spaced 1.5 nm radius circular pores. The time dependent diffusion wake model in this study provides a new interpretation of labeled tracer studies to define the permeability pathways for low molecular weight tracers which depend on the time dependent filling of the extravascular space. This model and recent microscope experiments with low molecular weight fluorescent probes support the existence of a previously unrecognized family of {dollar}\sim{dollar}2 nm small pores that are distributed along the length in the junction strand. Furthermore, the convective-diffusion wake model developed herein, in conjunction with related experiments, is designed to evaluate the relative contribution of structures associated with the junctional strand and the fiber matrix to the molecular filter at the microvessel wall.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
