Coagulation factors and permeability processes

Abstract

As an experimental model for capillary permeability we investigated the behavior of fluorescent labeled proteins by means of vital fluorescence microscopy of the rat mesentery exposed into a transparent superfused chamber. Fluorescent labeled proteins injected intravenously pass through the vascular wall, preferably at the venous site of the microvasculature, spread into the perivascular interstitial tissue and appear eventually in the regional lymph vessels. By various experimentally induced changes of the coagulation system we found alterations of the permeability processes. In states of hypocoaguability the passages of proteins through the vascular wall and within the interstitial space are augmented. Proteins are transported more rapidly and in greater amounts from the blood into the perivascular tissue.

An anatomico-topographical affinity of coagulation factors to the vessel wall of the microcirculation has been investigated by the same technique injecting fluorescent labeled coagulation factors. We found a peculiar accumulation of fibrinogen, at the vascular wall, especially at the inner lining of venules, prefering the interendothelial cellular borders. Those places showed also an increased permeability of the labeled fibrinogen. We did not found similar affinities except with factor VIII and fibronectin.

At present we can only speculate about the exact pathophysiological mechanisms of the relations between coagulation and capillary permeability found in these and other investigations.