THE INFLUENCE OF COUMARIN ON TISSUE LEVELS OF RADIO‐LABELLED PLASMA PROTEIN AND POVIDONE (POLYVINYLPYRROLIDINE) IN NORMAL AND THERMALLY INJURED RATS

1. The administration of coumarin resulted in a two‐fold increase in the entry of ⁵¹Cr‐labelled rat plasma protein into otherwise normal tissues. 2. Prior treatment of rats with coumarin allowed about 50% more radio‐labelled protein to enter the tissues immediately after thermal injury than occurred with thermal injury in untreated rats. 3. In coumarin‐treated rats, 30 min or more after thermal injury, tissue levels of ¹²⁵I‐labelled povidone (polyvinylpyrrolidine) were significantly elevated or showed no change compared with tissue levels in rats which received only thermal injury. 4. Conversely, tissue levels of radio‐labelled protein in coumarin‐treated rats, 30 min or more after thermal injury were significantly reduced to between 20 and 30% of those in untreated, thermally injured rats. 5. These results were attributed to enhanced proteolysis of the radio‐labelled protein caused by coumarin. Other results have shown that normal protein is similarly affected. 6. The products of proteolysis may then rapidly leave the tissues, freeing the osmotically‐held fluids and reducing the oedema.