Abstract
Lecithin:cholesterol acyltransferase (LCAT) and cholesteryl ester (CE) transfer activity accumulate linearly in the recirculated medium of the isolated perfused rabbit liver. The appearance of both activities in the perfusate was blocked by the addition of 10 microM colchicine, indicating that these two proteins are synthesized and secreted by the liver. CE transfer activity catalyzed the net transport of cholesteryl ester from high density lipoprotein (donor) to very low and low density lipoproteins (acceptor), both in the perfusate medium and in whole rabbit blood plasma. The activity of LCAT in the perfusate was dependent on the presence of the major protein of the high density lipoprotein class, apoA-I. The similar properties of LCAT and CE transfer activity in rabbit liver perfusate and plasma, compared to these same activities in human blood, suggest that the rabbit is an appropriate model for the study of the cholesterol transport system in man.
Highlights
Lecithin:cholesterolacyltransferase(LCAT)and cholesteryl ester (CE) transfer activity accumulate linearly in the recirculated medium of the isolated perfused rabbit liver
T o determine net transport of CE in rabbit plasma or perfusate, LCAT was inhibited by DTNB and transport was measured as the amount of high density lipoprotein (HDL)-CE mass transferred to very low density lipoprotein (VLDL) and low density lipoprotein (LDL)
The acceptor particles were precipwere investigated on samples of medium from which en- itated with dextran sulfate and MgCI2, and the superdogenous VLDL secreted by the liver during the exper- natant was assayed both in terms of CE mass and radioiment was first removed by centrifugation at a density of activity
Summary
Lecithin:cholesterolacyltransferase(LCAT)and cholesteryl ester (CE) transfer activity accumulate linearly in the recirculated medium of the isolated perfused rabbit liver. T o determine net transport of CE in rabbit plasma or perfusate, LCAT was inhibited by DTNB and transport was measured as the amount of HDL-CE mass transferred to VLDL and LDL. CE transfer activity, measured with the exogenous substrate assay, accumulated at a rate of 2.9 f 1.2 nmol h-' perfusion g-' of liver (n = 11).
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