Benzo‐pyrones: their selective injury to rabbit vascular endothelium

1. Three benzo‐pyrones were tested in two types of high protein oedema. 2. In general, they prevented increases in permeability in superficial venules. 3. In the absence of an injurious stimulus they caused injury to the superficial capillaries and deep venules. 4. The injurious results may be due to a direct effect on the vessel walls or to an increase in intravascular pressure and flow. This would enhance leakage from already existing defects. 5. Despite the minor injuries the effectiveness of these drugs is so great that a net removal of protein by proteolysis from the tissues occurs, thus reducing the oedema. 6. The study contributes further to an understanding of the mode of action of the benzo‐pyrones.