Metabolism of a lipid nanoemulsion resembling low-density lipoprotein in patients with grade iii obesity

Abstract

Introduction: Obesity increases triglyceride levels and decreases high-density lipoprotein concentrations in plasma. Artificial emulsions resembling lipidic plasma lipoprotein structures have been used to evaluate low-density lipoprotein metabolism. In grade III obesity, low density lipoprotein metabolism is poorly understood.

Objective: To evaluate the kinetics with which a cholesterol-rich emulsion (called a low-density emulsion) binds to low-density lipoprotein receptors in a group of patients with grade III obesity by the fractional clearance rate.

Methods: A low-density emulsion was labeled with [(14)C]-cholesterol ester and [(3)H]-triglycerides and injected intravenously into ten normolipidemic non-diabetic patients with grade III obesity [body mass index higher than 40 kg/m(2)] and into ten non-obese healthy controls. Blood samples were collected over 24 hours to determine the plasma decay curve and to calculate the fractional clearance rate.

Results: There was no difference regarding plasma levels of total cholesterol or low-density lipoprotein cholesterol between the two groups. The fractional clearance rate of triglycerides was 0.086 +/- 0.044 in the obese group and 0.122 +/- 0.026 in the controls (p = 0.040), and the fractional clearance rate of cholesterol ester (h(-1)) was 0.052 +/- 0.021 in the obese subjects and 0.058 +/- 0.015 (p = 0.971) in the controls.

Conclusion: Grade III obese subjects exhibited normal low-density lipoprotein removal from plasma as tested by the nanoemulsion method, but triglyceride removal was slower.

Keywords: LDL metabolism; artificial emulsions with lipidic structure; grade III obesity; radioisotopes; triglyceride.

Figure 1

Decay curves of the [³H]-triglyceride emulsion obtained from obese and control subjects. The labeled emulsion was intravenously injected in a bolus, and blood samples were drawn at pre-established intervals over 24 h for measurement of radioactivity in a scintillation solution.

Figure 2

Decay curves of the [¹⁴C]-cholesteryl oleate emulsion obtained from obese and control subjects. The labeled emulsion was intravenously injected in a bolus, and blood samples were drawn at pre-established intervals over 24 h for measurement of radioactivity in a scintillation solution.