Variations in acid and neutral protease activity of rats with thermal oedema together with the influence of various benzopyrones.

The benzopyrones are known to be very effective in reducing thermal oedema. It is believed they do this by enhancing protoelysis of the abnormal accumulated protein. However, the enzymes which are affected were not known. The effect of the benzopyrones was examined on both acid and neutral proteases in normal and thermally injured animals. In normal animals the benzopyrones at first enhanced serum acid protease levels, while serum neutral protease levels were depressed. Acid and neutral protease levels of the skin were not altered. The effect of thermal injury was to elevate serum acid protease activity and to depress neutral protease activity. Additional treatment with the benzopyrones further enhanced the former and depressed the latter. Acid and neutral protease activity of the skin was depressed by burn, but enhanced by benzopyrone treatment. The enhancement of proteolytic activities by the bezopyrones is indicative of increased phagocytosis and digestion. The resulting small protein fragments can rapidly leave the injured region thus freeing the osmotically attracted fluid, which is the cause of oedema.