Exchange of free cholesterol between low density lipoproteins and human adipocytes
Autor: | J. A. Nettleton, R. Yuen, A. Angel |
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Rok vydání: | 1981 |
Předmět: |
Intermediate-density lipoprotein
medicine.medical_specialty Dose-Response Relationship Drug Chemistry Reverse cholesterol transport Adipose tissue Blood lipids General Medicine Cholesterol LDL In Vitro Techniques Lipoproteins LDL Free cholesterol Kinetics Endocrinology Cholesterol Biochemistry Adipose Tissue Internal medicine Collagenase medicine Low density Humans lipids (amino acids peptides and proteins) Lipoproteins HDL medicine.drug |
Zdroj: | Canadian journal of biochemistry. 59(8) |
ISSN: | 0008-4018 |
Popis: | Free cholesterol uptake from low density lipoproteins (LDL) by fat cells was investigated using exchange-labelled [1,2-3H]cholesterol–LDL and isolated human adipocytes, prepared by collagenase digestion of subcutaneous fat tissue biopsies. Radioactivity appeared in the cellular lipids within 2 min and accumulated at a slower rate approaching linearity for 3 h. At 5 and 120 min, 90% of the recovered cellular radioactivity was found in the bulk lipid fraction and the remainder was distributed among organelle fractions. Uptake of [3H]cholesterol was linearly related to substrate concentrations up to 5 μg unesterified cholesterol – LDL∙mL−1. At higher concentrations up to 22 μg unesterified cholesterol – LDL∙mL−1, [1,2-3H]cholesterol accumulated more gradually but did not reach a plateau. Metabolic inhibitors, sodium azide plus sodium fluoride, had no effect on radiocholesterol uptake. Native LDL and high density lipoprotein at equivalent unesterified cholesterol concentrations decreased [1,2-3H]cholesterol uptake, to a similar extent suggesting isotope dilution. The results demonstrate a rapid, receptor-independent uptake of cholesterol from LDL by adipocytes, consistent with an exchange mechanism. This process could explain the rapid labelling of adipose tissue cholesterol in vivo following intravenous administration of radiocholesterol and efflux of free cholesterol from adipose tissue during starvation. |
Databáze: | OpenAIRE |
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