Effect of prostaglandin E2 on the permeability of the iris vessels to horseradish peroxidase in the rabbit.

Prostaglandin E2 (0.5 microgram in 10 microliter 10% ethanol) was introduced into the anterior chambers of rabbit eyes. Using the horseradish peroxidase method, it was shown under the electron microscope that the endothelial barrier of the iris vessels broke down. The peroxidase penetrated as far as the basis of the posterior epithelial cells, however, without entering their lateral intercellular spaces. The question of whether the effect of prostaglandins on the barrier was a direct effect or at least a partially indirect one, i.e., a haemodynamic action, is discussed.