Focal endothelial cell injury in rabbit aorta, aggravation of injury by 2 days of cholesterol feeding.

A randomized morphometric study of "spontaneous" endothelial cell injury in rabbit aorta was performed blindly. Four different areas of the aorta were sampled in a standardized fashion and examined by scanning electron microscopy. The finding of protruding endothelial cells was taken as sign of injury. The endothelial cell injury was focal and, in the sampled areas, particularly prevalent in the distal part of the lesser curvature of the aortic arch and the distal lip of intercostal artery orifices. In the area between two intercostal artery orifices on the same side of the midline injured cells were only exceptionally found. Rabbits fed a 2% cholesterol diet for 2 days showed an increase in protruding cells, particularly at the intercostal artery orifices. It is concluded that the endothelial cell injury in rabbit aorta may be caused by local factors, determining the focal nature, and by systemic factors, such as acute hypercholesterolemia.