Combined junction-orifice-fiber entrance layer model for capillary permeability

B. H. Fu, F. E. Curry, R. Y. Tsay, S. Weinbaum

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The recent serial section electron microscopic studies by Adamson and Michael (1993) of frog mesentery have revealed that the large pores in the junction strand of the interendothelial clefts are widely separated 150 nm wide orifice-like breaks whose gap height 20 nm is the same as the wide part of the cleft. In this paper a modified version of the model in Weinbaum et al. (1992) is first developed in which this orifice structure is explored in combination with a random or ordered fiber matrix layer that occupies a fraction of the wide part of the cleft, This basic orifice model predicts that for the measured Lp 2.0 × 10.7cm/s/cm H2O, 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. The model provides a much better fit of the diffusive permeability P for intermediate size solutes between 1 and 2 nm radius than the previous model in Weinbaum et al. where the junction strand breaks were treated as finite depth circular or rectangular pores, but like the previous model significantly underestimates P for small ions. However, it is shown that if a continuous narrow slit of approximately 1.5 nm gap height is also present in the continuous part of the junction strand, small ion permeability can also be satisfied. The continuous narrow slit provides a contribution to Lp that is comparable to the widely spaced 150 nm orifices. Thus, for the narrow slit the contribution to Lp from the orifices can be as low as 1.0 × 10.7cm/s/ cm H2O and it is also possible to satisfy the 2.5 fold increase in permeability that occurs when the matrix is enzymatically removed from the luminal side of the cleft.

Original languageEnglish (US)
Title of host publicationAmerican Society of Mechanical Engineers, Bioengineering Division (Publication) BED
EditorsJohn M. Tarbell
Place of PublicationNew York, NY, United States
PublisherPubl by ASME
Number of pages4
ISBN (Print)0791810313
StatePublished - 1993
Externally publishedYes
EventProceedings of the 1993 ASME Winter Annual Meeting - New Orleans, LA, USA
Duration: Nov 28 1993Dec 3 1993


OtherProceedings of the 1993 ASME Winter Annual Meeting
CityNew Orleans, LA, USA

ASJC Scopus subject areas

  • Engineering(all)


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