The effect of coumarin on protein and PVP clearance from rat legs with various high protein oedemas

Coumarin (a benzopyrone) has been shown to bring about the rapid removal of protein from normal or burnt tissues and from those with lymphedema, with or without burning. This was particularly evident when the removal of protein was compared with that of a non metabolizable control, viz. polyvinyl pyrrolidone (PVP). The mode of action seems to be by stimulation of proteolysis. The fragments of protein could then rapidly leave the tissues because of their small size, their high diffusion coefficients and a concentration gradient which was directed from the tissues to the blood. In this way excessive amounts of protein could be removed, thus releasing the edema fluid. The removal of non metabolizable PVP was reduced with normal and burnt legs, possibly because of stimulated phagocytosis. In the presence of lymphedema there was a more rapid removal of PVP with coumarin; this was possibly a consequence of the great reduction of intercapillary distances resulting from the removal of edema fluid.