The Bi-directional Transfer of Cholesterol in Normal Aorta,Fatty Streaks,and Atheromatous Plaques 1

Summary

Isotopic cholesterol was administered per os for 30 days to cholesterol-fed White Carneau pigeons. At weekly intervals and for 100 days after cessation of isotope administration, subgroups were killed and their aortas were divided into normal tissue, fatty streaks, and atherosclerotic plaques. Cryostat sections from each plaque were examined for morphologic features, and from the different areas of the aorta cholesterol concentration and radioactivity were determined. From the values obtained, rates of influx and efflux of plasma cholesterol were calculated. The results indicated that in normal aorta the influx of free cholesterol greatly exceeds that of cholesteryl esters. There appeared to be no net positive cholesterol balance. In fatty streaks, the influx of both free and esterified cholesterol was greater than for normal tissue, and influx rates exceeded those for efflux. In plaques, still greater rates of influx and efflux were seen, and the influx of cholesteryl esters frequently exceeded that of free cholesterol, and like fatty streaks, plaques appeared to be in positive cholesterol balance. No relationship was observed between the morphologic and metabolic characteristics of the plaques.