Effect of removal of atherogenic diet on protein synthesis and cholesterol retention in rabbit aorta and lung.

The purpose of these studies was to determine the effect of cholesterol feeding in rabbits on the synthesis of collagen and non-collagen proteins in both aortic and lung tissues. Rabbits were fed a 2% cholesterol diet for 30 or 60 days, followed by 30 days of a low cholesterol diet (i.e. 30-30 or 60-30). After 30 days of cholesterol feeding non-collagen protein synthetic rates were significantly elevated in aortic tissues, but not in the lung. After 60 days of cholesterol feeding, both collagen and non-collagen synthetic rates were elevated in the aorta but not in the lung. Both tissues demonstrated significant increases in cholesterol content. When cholesterol was removed from the diet, cholesterol continued to accumulate in the aorta but decreased in the lung. The 60-30 group demonstrated both the largest increase in aortic cholesterol, and the largest increase in the per cent of collagen being synthesized in the aorta. These data therefore demonstrate that cholesterol feeding stimulates both collagen and non-collagen protein synthesis and suggests that there may be some differences in the lag phase before significant changes are apparent in both parameters. Following removal of cholesterol from the diet the per cent collagen synthesized in the aorta increased further, due to an apparent reduction in non-collagen protein synthesis rather than a further acceleration of collagen synthesis. These changes may be important in explaining how intermittent-cholesterol feeding produces a more fibrous aortic lesion.