Aortic changes induced by hypercholesterolemia and hypercalcemia in rats.

The effects of vitamin D and cholesterol-rich diets on rat aortas were examined. Examination by electron microscopy showed a widening of the subendothelial space and the presence in this space of amorphous substances as early as the second week into mild hypercholesterolemia. After further time elapsed, basement membrane-like substances, microfilaments, migration of mononuclear cells, and modified smooth muscle cells were seen in the subendothelial space. In the vitamin D group, the main electron microscopic finding was of medial smooth muscle cell changes, such as focal degeneration and matrix vesicles. However, calcification was not observed in our present study. In rats fed a cholesterol-rich diet plus vitamin D, changes associated with both the cholesterol-rich diet only and vitamin D only were seen.