Decreased plasma membrane fluidity in the development of atherosclerosis in cholesterol-fed rabbits

Rabbits were fed a diet supplemented with 3% peanut oil or 3% peanut oil plus 0.5% cholesterol. Aortas from rabbits fed the cholesterol supplemented diet for 2 weeks were free of grossly visible lesions; however, aortas from rabbits fed this diet for 10 weeks exhibited extensive lesion development. Lesions were not observed in aortas of rabbits fed the high-fat supplemented diet. The fluorescence anisotropy of DPH was significantly (P = 0.0001) increased in plasma membranes isolated from aortas of rabbits fed the high-fat plus cholesterol vs. high-fat supplemented diet; the increase in fluorescence anisotropy observed after only 2 weeks on diet (0.201 +/- 0.002 vs. 0.144 +/- 0.002) was similar to that observed after 10 weeks on diet (0.244 +/- 0.002 vs. 0.193 +/- 0.001). The data support the hypothesis that plasma membrane fluidity [is decreased in atherosclerosis and indicate the decrease in membrane fluidity] occurs early in the development of the disease.