Transient regulation of transport by pericytes in venular microvessels via trapped microdomains

X. Zhang, R. H. Adamson, F. E. Curry, S. Weinbaum

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


A phenomenon that has defied explanation for two decades is the time scale for transient reabsorption in the classic experiments of Michel and Phillips on individually perfused frog mesentery microvessels. One finds that transient reabsorption lasts <2 min before a new steady state of low filtration is established when the lumen pressure is abruptly dropped from a high to a low value. Our experiments in frog and rat venular microvessels under a variety of conditions revealed the same time trend for new steady states to be established as in Michel and Phillips' experiments. In contrast, one theoretically predicts herein that the time required for the tissue albumin concentration to increase to values for a new steady state to be achieved through reabsorption is in the order of several hours. In this paper we propose a new hypothesis and theoretical model for this rapid regulation, namely that pericytes covering the interendothelial cleft exits create small trapped microdomains outside the cleft exits which regulate this transient behavior. Our electron microscopy studies on rat mesenteric venular microvessels reveal an average pericyte coverage of ≈85%. The theoretical model based on this ultrastructural study predicts an equilibration time on the order of 1 min when the lumen pressure is abruptly lowered. The basic concept of a trapped microdomain can also be extended to microdomains in the interstitial space surrounding skeletal muscle capillaries.

Original languageEnglish (US)
Pages (from-to)1374-1379
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number4
StatePublished - Jan 29 2008


  • Microvascular exchange
  • Pericyte regulation
  • Revised starling hypothesis
  • Trapped microdomains
  • Venous reabsorption

ASJC Scopus subject areas

  • Genetics
  • General


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