Vascular permeability to macromolecules changes qualitatively in inflammation?

The time courses of vascular permeability to native bovine serum albumin (BSA), cationized BSA, dextran (mol wt. 40,000) and bovine immunoglobulin G (IgG) in carrageenin-induced inflammation in rats were determined by the fluorometric method. The vascular permeability to BSA increased gradually until about 5 hr after carrageenin injection. The vascular permeabilities to dextran and IgG reached a maximum at 1 hr after carrageenin injection and then decreased. In the early-stage, 0-1 hr after carrageenin injection, dextran was the most permeating of the three. However, in the later-stage, 3-5 hr after carrageenin injection, BSA became the most permeating. Furthermore, cationized BSA was more permeating than native BSA having a negative charge in the early-stage, but the difference between the permeability to cationized BSA and native BSA was decreased at the later-stage. These data suggest that vascular permeability changes qualitatively in carrageenin-induced inflammation in rats, and it is unlikely that the increased vascular permeability is caused by the ultrafiltration through gaps formed between endothelial cells.