Chapter 6. Transport of Material Between Blood and Wall in Arteries

  1. Ruth Porter and
  2. Julie Knight
  1. C. G. Caro

Published Online: 30 MAY 2008

DOI: 10.1002/9780470719954.ch6

Ciba Foundation Symposium 12 - Atherogenesis: Initiating Factors

Ciba Foundation Symposium 12 - Atherogenesis: Initiating Factors

How to Cite

Caro, C. G. (1973) Transport of Material Between Blood and Wall in Arteries, in Ciba Foundation Symposium 12 - Atherogenesis: Initiating Factors (eds R. Porter and J. Knight), John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/9780470719954.ch6

Author Information

  1. Physiological Flow Studies Unit, Imperial College, London

Publication History

  1. Published Online: 30 MAY 2008
  2. Published Print: 1 JAN 1973

ISBN Information

Print ISBN: 9789021940137

Online ISBN: 9780470719954

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Keywords:

  • arteries;
  • atheromatous lesions;
  • carotid artery;
  • reynolds number;
  • curved tubes

Summary

Certain early atheromatous lesions in man (early plaques and fatty streaks) have been shown to occur preferentially in regions in arteries where wall shear rate is expected to be low. Moreover, there is evidence obtained in vivo that the transport of certain material between intraluminal blood and the artery wall is increased by wall shear Based on these findings the hypothesis was proposed that the development of these early lesions is related to locally reduced efflux of accumulating material, from wall to blood, due to locally reduced wall shear rate. No detailed study has, however, been made of the mechanics of the transport of a material between intraluminal blood and artery wall. Theory is developed and studies are reported in which an isolated common carotid artery from a dog is perfused, in a special rig, with serum containing labelled cholesterol. It is assumed that the transport is predominantly by mass diffusion, rather than bulk flow. Three steps must then be involved: diffusion across a boundary layer; uptake at the wall surface; and transport within the wall. The first step (and uptake by the wall) can be predicted if the diffusion boundary layer is rate limiting for the total process. Poiseuille flow is developed in the artery segment, which is supported at either end by impermeable tubing. Then, despite spatial constancy of wall shear rate, there will be spatial dependence of uptake, due to growth of the diffusion boundary layer along the segment, and a dependence of uptake, at any station, on wall shear rate. It was found (39 experiments) that wall uptake was on average spatially uniform and the rate of uptake was less by 102--103 than predicted from diffusion boundary layer theory, for cholesterol associated with lipoprotein. These findings, together with enhancement of uptake after alcohol damage to the wall, are inconsistent with the diffusion boundary layer being rate controlling. In eight out of nine paired studies, increase of wall shear increased uptake of label by the wall but there was appreciable uptake with zero wall shear. It appears that the uptake process at the wall surface is rate controlling and that this process, which has yet to be characterized, is shear dependent.