Lipid emulsions (LE) contain triglyceride (TG)-rich particles (TGRP) and ph
ospholipid-rich particles (PLRP). Various lipid and protein exchanges take
place during in vitro incubations of LE with lipoproteins. These compositio
n changes affect physical properties of particles. The aim of this study wa
s to determine the role of different LE particles and the effect of TG comp
osition on physical modifications. Low density lipoproteins (LDL: 1.025 < d
< 1.040 g/mL) or high density lipoproteins (HDL: 1.085 < d < 1.150 g/mL) w
ere incubated with the following four LE or their TGRP or PLRP, which were
manufactured with the same phospholipid emulsifier: long-chain triglyceride
s (LCT): 100% soybean oil; medium-chain triglycerides (MCT)/LCT (MCT/LCT, 5
:5, w/w); FO (100% fish oil); and MLF541 (MCT/LCT/FO, 5:4:1, by wt). After
incubation, modified LE particles and lipoproteins were analyzed by fluores
cence polarization. Observed physical modifications were significant in emu
lsion particles (ordering effect) but not in lipoproteins and also were sig
nificant for TG composition effect. Since intact emulsion contained a large
excess of TGRP over PLRP, it is not surprising that intact emulsion had th
e same behavior as TGRP alone, and that PLRP had the same physical characte
ristics as lipoproteins. TG loss and cholesterol and protein acquisitions b
y emulsion particles rigidify their envelope. The two emulsions containing
FO were less ordered after incubation. In conclusion, incubation of LE with
lipoproteins changes physical properties of each kind of particle, and TG
composition of the emulsion affects emulsion particle changes but has no ef
fect on LDL and HDL. These order modifications induce more effective exchan
ges between LE particles and lipoproteins and modify their metabolism; HDL
changes may increase the reverse cholesterol transport.