Mesenteric microvascular inflammatory responses to systemic hypoxia are mediated by PAF and LTB4

Alfred J. Casillan, Norberto C. Gonzalez, Jennifer S. Johnson, Dawn R.S. Steiner, John G. Wood

Research output: Contribution to journalArticlepeer-review


Systemic hypoxia produces a rapid microvascular inflammatory response characterized by increased reactive oxygen species (ROS) levels, leukocyte-endothelial adherence and emigration, and increased vascular permeability. The lipid inflammatory mediator leukotriene B4 (LTB4) is involved in the early hypoxia-induced responses (ROS generation and leukocyte adherence). Whether other lipid inflammatory mediators participate in this phenomenon is not known. The objective of these experiments was to study the role of platelet-activating factor (PAF) in the microvascular inflammatory response to hypoxia and its potential interactions with LTB4 in this response. Intravital microscopy was used to examine mesenteric venules of anesthetized rats. We found that WEB-2086, a PAF receptor antagonist, completely prevented the increase in ROS levels and leukocyte adherence during a brief reduction in inspired PO2 to anesthetized rats; administration of either WEB-2086 or the LTB4 antagonist LTB4-DMA attenuated leukocyte emigration and the increase in vascular permeability to the same extent during prolonged systemic hypoxia in conscious rats. Furthermore, no additive effect was observed in either response when both antagonists were administered simultaneously. This study demonstrates a role for PAF in the rapid microvascular inflammatory response to hypoxia, as well as contributions of PAF and LTB4 to the slowly developing responses observed during sustained hypoxia. The incomplete blockade of the hypoxia-induced increases in vascular permeability and leukocyte emigration by combined administration of both antagonists indicates that factors in addition to LTB4 and PAF participate in these phenomena.

Original languageEnglish (US)
Pages (from-to)2313-2322
Number of pages10
JournalJournal of applied physiology
Issue number6
StatePublished - Jun 1 2003
Externally publishedYes


  • Inflammatory mediators
  • Intravital microscopy
  • Leukocyte emigration
  • Leukocyte-endothelial adhesive interactions
  • Microcirculation

ASJC Scopus subject areas

  • General Medicine


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