Endothelial structure in rabbits with moderate hypercholesterolaemia. A scanning electron microscopic study.

The aortic surface of rabbits given a supplement of 0.1--0.3 per cent cholesterol to the diet was studied by scanning electron microscopy. In regions where increased haemodynamic strain was anticipated, similar structural changes were observed in normal and hypercholesterolaemic rabbits. However, changes indicating cell injury were more wide-spread in cholesterolfed animals. This suggests that hypercholesterolaemia may increase cell susceptibility to injury. In the same regions, the development of intimal thickenings was observed in cholesterol-fed rabbits. The central parts of such thickenings had been reendothlialized, whereas a region with cell injury surrounded each lesion. In regions with low haemodynamic strain, a loss of fine-structural details was observed in hypercholesterolaemic rabbits. It is suggested that these changes may be related to the deteriorated functional properties of the intact endothelium in such rabbits. In view of these data it is suggested that the interrelationship between hypercholesterolaemia and atherosclerotic arterial disease may partly be due to a deleterious effect of hypercholesterolaemia on the functional and structural integrity of the arterial endothelium.