Effects of contrast agents on the blood-brain barrier. An electron microscopic study.

To determine if contrast agents after the blood-brain barrier by opening tight junctions between endothelial cells and by increasing pinocytosis, the distribution of horseradish peroxidase (HRP) was evaluated after intracarotid injections of contrast media. HRP did not cross the endothelium of cerebral blood vessels. Tight junctions remained closed. There was increased endothelial cell pinocytosis and swelling of astrocyte end-feet.