ANIMAL AND PLANT FATS SELECTIVELY MODULATE OXIDIZABILITY OF RABBIT LDL AND LDL-MEDIATED DISRUPTION OF ENDOTHELIAL BARRIER FUNCTION

Enrichment of lipoproteins with fatty acids derived from animal and/or plant fats may modify the oxidizability of lipoproteins and their effects on endothelial barrier function. To test this hypothesis, rabbits were fed for 30 days diets containing 2 g corn oil/100 g diet (low fat diet) or low fat supplemented with 16 g/100 g diet of corn oil, corn oil with added cholesterol, milk fat, chicken fat, beef tallow or lard. Compared with those fed the low fat, serum and LDL cholesterol concentrations were significantly lower in rabbits fed corn oil and greater in animals fed corn oil with added cholesterol or chicken fat. In contrast to the cholesterol data, lipid hydroperoxide levels were highest in oxidized LDL derived from rabbits fed corn oil or lard. LDL vitamin E levels were highest in rabbits fed corn oil with added cholesterol. The significant elevations in linoleic acid [18:2(n-6)) in serum and LDL may partially explain the high oxidizability of LDL in rabbits fed corn oil. LDL isolated from animals fed corn oil, lard or milk fat had significantly greater albumin transfer across cultured endothelial monolayers compared with those of the low fat diet group. Their oxidative modification further contributed to endothelial barrier dysfunction. Dietary cholesterol supplementation to the corn oil diet decreased the oxidizability of LDL and partially protected the oxidized LDL-mediated endothelial cell dysfunction as compared with the corn oil diet group. These data suggest that beef tallow and chicken fat are the least atherogenic fats if oxidative modification of LDL is a critical issue in atherosclerosis.