Influence of arteriovenular pairing on PAF-induced capillary filtration.
The purpose of this study was to determine the basic mechanism by which leukocyte-endothelial cell adhesion mediates platelet-activating factor (PAF)-induced increases in capillary fluid filtration rate. A modified Landis technique was used to observe fluid filtration from capillaries in the rat mesentery. Hypothetical mechanisms of increased filtration that were tested included 1) a direct action of leukocytes on endothelial cells during transit through the capillaries; 2) an upstream propagated response (via gap junction communication by adjacent endothelial cells) originating at sites of venular leukocyte adhesion; and 3) venule-to-arteriole communication, where mediators produced at the site of venular leukocyte adhesion reach a nearby paired arteriole that delivers the mediators to branching capillaries. Evidence was obtained in opposition to the first two hypotheses. However, in support of the third hypothesis, a significant correlation was found between the extent of arteriolar pairing to venules and the PAF-induced increase in capillary fluid filtration rate. These findings suggest that venule-to-arteriole communication might modify capillary filtration rate during acute inflammation.
Harris
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Department of Molecular and Cellular Physiology, Louisiana State University Medical Center, Shreveport, Louisiana 71130, USA.
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D000818:Animals; D001160:Arterioles / Q000502:physiology*; D002200:Capillary Resistance / Q000187:drug effects* / Q000502:physiology; D002448:Cell Adhesion / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology; D007962:Leukocytes / Q000502:physiology; D008297:Male; D008643:Mesentery / Q000098:blood supply; D008955:Models, Cardiovascular; D010972:Platelet Activating Factor / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014699:Venules / Q000502:physiology*
D010972:Platelet Activating Factor