The resolution of thermal oedema at various temperatures under coumarin treatment

The treatment of thermal edema with coumarin (a benzopyrone) was most effective when fast moving air of 20° was blown over the burnt rats. Coumarin has 2 main effects: one is to cause vascular injury thus allowing extra protein and fluid into the tissues; the other is to stimulate phagocytosis, enzyme production and thus proteolysis and a subsequent removal of protein and fluid from the injured tissues. At lower temperatures the injurious nature of coumarin is prominent. At medium range temperatures the proteolytic actions of coumarin outweigh its injurious nature. Resolution thus proceeds much more rapidly. At high temperatures resolution is slowed. This is a consequence of the antioxidant effect of coumarin on adrenaline and ambient temperature on peripheral dilation. The results obtained tie in well with those obtained by workers using water of equivalent temperature.