AJP - Gastrointestinal and Liver Physiology, Vol 251, Issue 6 772-G778, Copyright © 1986 by American Physiological Society
Microvascular actions of platelet-activating factor on rat gastric mucosa and submucosa
B. J. Whittle, T. Morishita, Y. Ohya, F. W. Leung and P. H. Guth
Intravenous infusion of platelet-activating factor (PAF or AGEPC) induces
extensive acute hemorrhagic damage in the ra gastric mucosa. The effects of
PAF have now been investigated on several microcirculatory parameters in
the rat gastric mucosa. Infusion of PAF (25-100 ng X kg-1 X min-1 iv)
dose-dependently reduced systemic arterial blood pressure and mucosal blood
flow, as determined by hydrogen gas clearance. Microscopic observation
likewise indicated a dose-dependent slowing of mucosal capillary blood
flow, as determined by red blood cell velocity after PAF infusion with
stasis of flow at the highest dose. These actions were not the consequence
of vasoconstriction, since there was no significant change in arteriolar
and venular vessel diameter in the submucosa during PAF infusion, although
a dose-related slowing and stasis of blood flow was observed. There was no
capillary leakage of plasma protein in the gastric mucosa during PAF
infusion, as determined by a fluorescence marker (FITC-BSA) technique. The
precursor and breakdown product, lyso-PAF (200 ng X kg-1 X min-1) had no
significant action on any of these microcirculatory parameters. These
observations support the suggestion that microvascular changes leading to
stasis may contribute to the ulcerogenic actions of PAF.
