LIPID-COMPOSITION OF AORTA OF WATANABE HERITABLE HYPERLIPEMIC AND COMPARABLY HYPERCHOLESTEROLEMIC FAT-FED RABBITS - PLASMA-LIPID COMPOSITION DETERMINES AORTIC LIPID-COMPOSITION OF HYPERCHOLESTEROLEMIC RABBITS

Aortic and plasma lipid compositions were compared during a 12-month period in Watanabe heritable hyperlipemic (WHHL), comparably hypercholesterolemic fat-fed and age-matched control rabbits to determine whether exposure to equivalent degrees of endogenous or exogenous hypercholesterolemia led to differences in the composition and concentration of lipids deposited in the artery wall. Although there were differences in the distribution of cholesterol among the lipoproteins in the WHHL and fat-fed rabbits, the contents of both free and esterified cholesterol in the aorta and plasma were elevated to levels equivalent to those in the control rabbits. The triglyceride contents of both plasma and aorta were elevated only in the WHHL rabbits. However, aortic total phospholipids were increased in both WHHL and fat-fed animals as compared to control rabbits. In the control rabbits, there was an age-dependent enrichment in aortic cholesteryl oleate content consistent with low density lipoprotein receptor-directed intracellular cholesteryl ester processing. A similar enrichment in cholesteryl oleate was not detected in either WHHL or fat-fed groups, suggesting that the plasma cholesteryl ester composition was the primary determinant of the aortic cholesterol composition. Thus, under chronic hypercholesterolemic conditions, deposition of lipids in the artery wall appears to be independent of LDL receptor activity in the arterial cells.