Effect of the composition of very low and low density lipoproteins on the rate of cholesterylester transfer from high density lipoproteins in man, studied in vitro.

The process of cholesterylester (CE) transfer is supposed to be a regulatory factor in the distribution of CE between lipoproteins. In addition to the activity of CE transfer protein, this process may be affected by acceptor lipoprotein characteristics. In this study the effect of the composition of different very low density lipoproteins (VLDL) and low density lipoproteins (LDL) on the ability to accept CE from HDL in vitro was investigated. [3H]-CE high density lipoprotein (HDL) (100 nmol CE) from one batch was incubated with VLDL (75 nmol CE), isolated from fifteen subjects for 4 h and separately with LDL (250 nmol CE), isolated from thirteen subjects for 16 h, both in the presence of lipoprotein-free plasma providing a source of cholesterylester transfer protein. The CE transfer rate of VLDL (range 1.34-2.84% [3H]-CE transferred h-1) was correlated to the triacylglycerol (TG):CE molar ratio (r: 0.63, P less than 0.05), to the phospholipid (PL):CE molar ratio (r: 0.75, P less than 0.01), to the protein (Pr):CE ratio (expressed in g nmol-1) (r: 0.72, P less than 0.01) and to the free cholesterol (FC):CE molar ratio (r: 0.69, P less than 0.01), but not to the FC:PL molar ratio (r: -0.08, NS). The CE transfer rate to LDL (range 1.18-3.59 nmol CE h-1) was correlated to the Pr:CE ratio (r: 0.72, P less than 0.01) and inversely to the FRC:PL molar ratio (r: -0.88, P less than 0.001), but not to the TG:CE molar ratio (r: 0.40, NS), nor to the FC:CE molar ratio (r: -0.37, NS).(ABSTRACT TRUNCATED AT 250 WORDS)