Mesenteric microvascular inflammatory responses to systemic hypoxia are mediated by PAF and LTB4
Department of Molecular and Integrative Physiology, The University of Kansas Medical Center, Kansas City, Kansas 66160 Systemic hypoxia produces a rapid microvascular inflammatory response characterized by increased reactive oxygen species (ROS) levels, leukocyte-endothelial adherence and emigration...
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Veröffentlicht in: | Journal of applied physiology (1985) 2003-06, Vol.94 (6), p.2313-2322 |
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Zusammenfassung: | Department of Molecular and Integrative Physiology, The
University of Kansas Medical Center, Kansas City, Kansas 66160
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 B 4 (LTB 4 ) 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
LTB 4 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 P O 2 to anesthetized rats;
administration of either WEB-2086 or the LTB 4 antagonist
LTB 4 -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 LTB 4 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 LTB 4 and PAF participate in
these phenomena.
leukocyte-endothelial adhesive interactions; leukocyte emigration; microcirculation; intravital microscopy; inflammatory mediators |
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ISSN: | 8750-7587 1522-1601 |
DOI: | 10.1152/japplphysiol.00047.2002 |