Vascular leakage through intraendothelial channels induced by cholera toxin in the skin of guinea pigs.

Guinea pigs were injected intravenously with Evans blue solution (1/2), 1, 5 and 22 hours after intradermal injection of Vibrio cholerae 569B toxin. Then they were fixed by perfusion with diluted Karnovsky's aldehyde mixture 1(1/2), 5, 10, 15 and 90 minutes later. In some cases, horseradish peroxidase was mixed in the dye solution, and chopped tissue slices were incubated histochemically. Dermal blood vessels from these samples were examined under the electron microscope. The fine structure of the endothelial junctions remained unchanged as compared with controls. However, extended rough surfaced endoplasmic reticulum was observed in the endothelial cells at 30 minutes after the toxin injection, when cutaneous bluing was not marked yet. At 22 hours after toxin injection, endothelial perikarya were filled with prominent Golgi complexes, multivesicular bodies and systems of caveolae and vesicles which coalesced, forming intraendothelial channels after diaphragms disappeared. Endothelial fenestrae were numerous in the attenuated portions.