POPULATION-DYNAMICS OF ARTERIAL CELLS DURING ATHEROGENESIS .9. SIMILARITY OF ENDOTHELIAL CELL LOSS OVER INTIMAL SMOOTH-MUSCLE CELL MASSES (CUSHIONS) IN AORTAS OF SWINE FED NORMOLIPIDEMIC AND HYPERLIPIDEMIC DIETS FOR 60 DAYS

The objective of this study was to ascertain whether the previously demonstrated increased endothelial cell loss over swine aortic intimal cell masses (cushion areas) was dependent on a hyperlipidemic diet being fed to the swine. Aortic endothelial cells were labeled with tritiated thymidine. Fifteen swine were placed on a lowcholesterol (mash) diet for 15 days, at which time five were sacrificed for baseline studies. Five of the remaining swine were continued on the mash diet while five were placed on a hyperlipidemic diet; these two experimental groups were killed on Day 75 of the experiment. The rate of endothelial cell growth, division patterns, and loss of labeled endothelial cells over intimal cell mass and non-intimal cell mass areas were calculated in the two groups by comparing the findings in these groups to the baseline group. While endothelial cell loss was greater over aortic intimal cell mass areas than over other parts of the aorta, the hyperlipidemic diet did not enhance this during the period of study. Endothelial cells were lost at a similar rate over intimal cell mass areas in both the normolipidemic mash group and the hyperlipidemic group. The hyperlipidemic diet did, however, produce a significant increase in the surface area of aorta occupied by intimal cell mass areas, presumably due to the effect of the diet on smooth muscle cells. The endothelial cells covering these areas also increased significantly in number. The increase was brought about by an increase in the number of dividing endothelial cells which more than equaled a decrease in the average number of progeny per endothelial cell. © 1979.