Quantification of plasma lipids and apolipoproteins in British Halflop rabbits. A comparison between normocholesterolemic rabbits, hypercholesterolemic rabbits (modified WHHL rabbits) and rabbits fed an atherogenic diet

Effects of injury on apoB kinetics and concentration in rabbit aorta

Endothelial injury or dysfunction and deposition of lipoproteins and cholesterol are key events during the development of atherosclerosis. We have studied the lipoprotein kinetics in arterial tissue in relation to endothelial injury and re-endothelialization. Endothelial injury was induced in rabbits by use of a balloon catheter. With a specific immunoradiometric assay, apoB levels in arterial tissue were measured at different time points for up to 10 weeks after injury. Forty-five minutes before being killed, the rabbits were injected with 125I-LDL, and influx of LDL was calculated from the accumulation of radioactivity in the arterial tissue. The concentration of apoB in the injured arterial tissue was four times higher than that in control arterial tissue (P < .0001). Within the lesion the concentration was as high in nonendothelialized as in re-endothelialized regions. The tissue pool of apoB was divided into a loosely bound fraction and a tightly bound fraction. The increase of apoB in the injured areas was primarily due to an increase in the tightly bound fraction. The influx of apoB was severalfold higher in nonendothelialized tissue than in re-endothelialized tissue or control areas (P < .005). When retention time was calculated, this was found to dramatically increase (by seven times) the tightly bound pool of apoB in the re-endothelialized areas. In addition to the large increase of a tightly bound apoB pool in injured areas, we found a prolonged retention time of apoB in the lesions, but only in the re-endothelialized areas.(ABSTRACT TRUNCATED AT 250 WORDS)

Atherosclerosis in rabbits identified as high and low responders to an atherogenic diet and the effect of treatment with a beta 1-blocker

In order to investigate whether initial plasma lipid concentrations could be used to distinguish between high and low responders to an atherogenic diet, rabbits were divided into 3 groups according to their plasma concentrations of cholesterol and phospholipids after 4 weeks on a standard rabbit diet. Plasma cholesterol and phospholipid levels were less than 0.5 mM, less than 1.1 mM, respectively, in group 1 (n = 17), greater than 0.5 mM, less than 1.1 mM, in group 2 (n = 13), and greater than 0.5 mM, greater than or equal to 1.1 mM, in group 3 (n = 14). After 7 weeks on a diet containing 0.25% cholesterol and 3% coconut oil, animals in groups 1 and 2 had a lower increase in their plasma lipid levels compared with group 3. Half of each group was then treated with the beta 1-adrenoceptor antagonist metoprolol during the next 14 weeks on the atherogenic diet. At the end of the study, the extent of atherosclerosis both in the aortas and in the coronary arteries of the control animals showed a positive correlation to plasma cholesterol and to plasma phospholipid concentrations integrated over time. The metoprolol-treated animals in groups 1 and 2 had a reduction of atherosclerosis compared with their respective controls. We conclude that subpopulations of rabbits that react differently on an atherogenic diet can be identified by their initial plasma lipid levels, and that metoprolol treatment of low responders to an atherogenic diet significantly reduces atherosclerotic lesions of the aorta.