Increased vascular permeability in the rabbit iris induced by prostaglandin E1

Prostaglandin E₁ (PGE₁) (25 g) was applied topically to the eyes of albino rabbits, and lanthanum was used as an electron microscopic tracer to study possible vascular permeability changes in the iris of these eyes. Lanthanum was injected directly into the blood circulation 15min after application of the PG, and the eyes were enucleated 30 or 60 min later. PGE₁Was found to induce increased vascular permeability. Heavy deposits of the tracer were found in the walls of iridial venules, especially between the endothelium and its basement lamina. The highest concentration of lanthanum was found in close relation to the interendothelial clefts. Occasionally, gaps between neighbouring endothelial cells were observed. In control eyes, not treated with PG, no extravasation of the tracer was found. The study indicates that the iridial blood vessels contribute to the production of the plasmoid aqueous humour induced by PGE₁ in the rabbit eye.This paper was presented in part at the 7th Annual Meeting of the European Club for Ophthalmic Fine Structure in Ystad, Sweden on April 20 and 21, 1979