Metabolic behavior in rats of a nonprotein microemulsion resembling low-density lipoprotein |
| |
Authors: | Raul C Maranhão Thais B Cesar Suzana R Pedroso-Mariani Mario H Hirata Carlos H Mesquita |
| |
Affiliation: | 1. Faculty of Pharmaceutical Sciences, S?o Paulo University, S?o Paulo, Brazil 2. The Heart Institute (Instituto do Cora??o do HC-FMUSP), S?o Paulo University, S?o Paulo, Brazil 4. Institute of Energy and Nuclear Research (IPEN-CNEN), S?o Paulo, Brazil
|
| |
Abstract: | A protein-free microemulsion (LDE) with a lipid composition resembling that of low-density lipoprotein (LDL) was used in metabolic
studies in rats to compare LDE with the native lipoprotein. LDE labeled with radioactive lipids was injected into the bloodstream
of male Wistar rats, and plasma kinetics of the labeled lipids were followed on plasma samples collected at regular intervals
for 12 h after injection. The 24-h LDE uptake by different tissues was also measured in tissue samples excised after the animals
had been sacrificed. We found that LDE plasma kinetics were similar to those described for native LDL fractional clearance
rate (FCR) of cholesteryl ester, 0.42±0.11 h−1]. The major site for LDE uptake was the liver, and the tissue distribution of the LDE injected radioactivity was as one would
expect for LDL. To test whether LDE was taken up by the specific LDL receptors, the LDE emulsion was injected into rats treated
with 17α-ethinylestradiol, which is known to increase the activity of these receptors; as expected, removal of LDE from the
bloodstream increased (FCR=0.90±0.35 h−1). On the other hand, saturation of the receptors that remove remnants by prior infusion of massive amounts of lymph chylomicrons
did not change LDE plasma kinetics. These results indicate that LDE is cleared from plasma by B,E receptors and not by the
E receptors that remove remnants. Incorporation of free cholesterol into LDE increased LDE plasma clearance. Incubation studies
also showed that LDE incorporates a variety of apolipoproteins, including apo E, a ligand for recognition of lipoproteins
by specific receptors. Our data suggest that LDE can be a useful tool to test LDL metabolism and B,E receptor function. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|