Changes of Serum Lipoproteins by Glycation (II)

Changes in HDL Composition by in vitro Glycation

Abstract

When sera were incubated at 37°C for 70 hr, cholesterol and phospholipids in high density lipoproteins (HDL) were reduced compared with control sera kept at 4°C, but triglycerides increased significantly. Cholesterol and phospholipids in HDL further decreased concomitantly with HDL levels after incubation with glucose, though HDL triglyceride did not change.
Concentrations of HDL₂ were not affected by incubation and there were no significant effect on other constituents in HDL₂ excluding increased triglyceride. Triglycerides in HDL₂ further increased by the addition of glucose but other HDL₂ constituents and HDL₂ concentrations decreased reversely.
HDL₃ concentrations decreased in both incubated sera with or without glucose because of the decreases of their constituents except increased triglyceride contents. The compositions of HDL₃ were almost similar in both incubated sera.
Cholesterol in d>1.21 fractions decreased and triglycerides as well as phospholipids increased after the incubation with or without glucose. But apoproteins in these fractions were not changed after the incubation, except increased apo C-III protein.
It is concluded that the most remarkable change in HDL by the addtion of glucose to the incubated sera is the decrease of HDL₂ fraction, which might be derived from increased transfer of cholesteryl esters to VLDL. Reduction of serum HDL levels is considered to be not caused from fragility of HDL particles, because lipids and apoproteins in d>1.21 fractions are not influenced by the addition of glucose.