Animals of various species are widely used as models with which to study
atherosclerosis and the
lipoprotein metabolism. The objective of this study was to investigate the
lipoprotein profiles in Wistar rats and New Zealand white rabbits with experimentally induced
hyperlipidemia by means of ultracentrifugation. The Schlieren curves were utilized to compare suckling and adult rat sera to determine whether aging causes alterations in
lipoprotein profiles. A striking feature of the data is the high concentration of
low-density lipoproteins (
LDL), (>5.2 mmol/l
cholesterol) in the 2-week old rat serum pool which was greatly decreased in the 3-weeks rat serum pool (<1.3 mmol/l
cholesterol). Additional experiments were performed to permit a direct comparison of the amounts of
lipoprotein present in rat sera in experimental
hyperlipidemia post-
Triton WR 1339 administration. Rapid changes in concentrations in
very low-density lipoproteins (VLDL),
LDL and
high-density lipoproteins (HDL) were observed after Triton injection. The administration of
Triton WR 1339 to fasted rats resulted in an elevation of serum
cholesterol levels. Triton physically alters VLDL, rendering them refractive to the action of lipolytic
enzymes in the blood and tissues, preventing or delaying their removal from the blood. Whereas the VLDL concentration was increased markedly, those of
LDL and HDL were decreased at 20 h after Triton treatment. Rabbits were fed a diet containing 2%
cholesterol for 60 days to develop
hyperlipidemia and atheromatous aortic plaques. A combination of preparative and analytical ultracentrifugation was used to investigate of
LDL aliquots, to prepare radioactive-labeled
lipoproteins and to study induced
hyperlipidemia in rabbits. Analytical ultracentrifugation was applied to investigate the
LDL flotation peaks before and after
cholesterol feeding of rabbits. Modified forms of
LDL were detected in the plasma of rabbits with experimentally induced
atherosclerosis.
ApoB-containing particles, migrating as
LDL,
intermediate density lipoproteins and VLDL were the most abundant
lipoproteins.
Gamma camera in vivo scintigraphy on rabbits with radiolabeled
lipoproteins revealed visible signals corresponding to
atherosclerotic plaques of the aorta and carotid arteries.