The permeability of arterial endothelium to horseradish peroxidase

Abstract

The protein horseradish peroxidase when injected intravenously into rats and mice rapidly begins to pass from the blood into the walls of arteries. It is found in the intercellular junctions of the endothelium and appears to be crossing the endothelial layer by this route. It is present also in the system of caveolae and vesicles, but it is not clear whether or to what extent these form a means of transport across this layer. It enters multi-vesicular bodies and other relatively large vesicles of the endothelium. Within a few minutes of injection it penetrates through elastic tissue and muscle layers and becomes widely dispersed in the tissue spaces of the media.