Mechanisms underlying enhanced capillary filtration induced by
platelet activating factor.
Harris, Norman R., D. Neil Granger.
Department of Physiology and Biophysics,Louisiana State University
Medical Center, Shreveport, Louisiana
APStracts 2:0298H, 1995.
Fluid filtration rate (Jv/S) from rat mesenteric capillaries was
measured prior to and following platelet-activating factor (PAF)
superfusion, a model of acute inflammation. Jv/S increased from a
baseline value of .015 +/- .003 to .033 +/- .003 [mu]m/s (N=7 rats,
p<.001) during PAF superfusion. Measurements of arteriolar
pressure with a servo-nulling pressure system suggest that the
dominant factor causing the increase in Jv/S during PAF superfusion
is increased capillary permeability, rather than an increase in
pressure. Jv/S did not increase when PAF superfusion was preceded by
administration of the radical scavenging enzymes catalase and
superoxide dismutase, implicating a role for oxygen radicals in the
PAF-induced capillary filtration. In another series of studies, three
experiments were performed, i.e., PAF superfusion alone or PAF
superfusion plus treatment with either a soluble form of sialyl
-Lewisx (SLex) or a nonbinding form of SLex (SLN). These experiments
revealed that the increased Jv/S normally elicited by PAF is
significantly blunted by administration of soluble SLex, but not by
the control oligosaccharide SLN. The results of this study invoke a
role for oxygen free radicals and selectins (ligands for SLex) in the
enhanced capillary fluid filtration elicited by PAF.
Received 8 December 1994; accepted in final form 30 June 1995.
APS Manuscript Number H1074-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 18 July 1995.