β-Carotene transport in human lipoproteins. Comparisons with a-tocopherol |
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Authors: | Maret G Traber Seth R Diamond Jerome C Lane Rachel I Brody Herbert J Kayden |
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Affiliation: | (1) Department of Pediatrics, New York University School of Medicine, 10016 New York, New York;(2) Department of Pathology, New York University School of Medicine, 10016 New York, New York;(3) Department of Cell and Molecular Biology, Unvieristy of California, 94720 Berkeley, CA;(4) Present address: University of Cincinnati School of Medicine, 45267 Cineinnati, OH;(5) Department of Medicine, NYU Medical Center, 550 First Avenue, 10016 New York, NY |
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Abstract: | The purpose of this study was to investigate the temporal relationships of the transport of β-carotene in human lipoproteins.
We administered 60 mg β-carotene with breakfast to nine fasting subjects, then blood samples were collected at intervals of
up to 75 h, lipoproteins were isolated, and β-carotene was quantitated. β-Carotene concentrations in chylomicrons and very
low density lipoproteins (VLDL) peaked at 6 and 9 h, respectively. Nonetheless, at all time points the majority of plasma
β-carotene was contained in low density lipoproteins (LDL), while high density lipoproteins (HDL) carried a smaller portion
(at 24 h, 73±8% in LDL as compared with 23±5% in HDL). In three subjects, transport of β-carotene was compred with the results
of earlier studies on the transport of stereoisomers of α-tocopherol. Unlike plasmaRRR-α-tocopherol concentrations, which are maintained by the preferential incorporation ofRRR-α-tocopherol into VLDL by the liver, β-carotene increased and decreased in VLDL similarly toSRR-α-tocopherol, a stereoisomer whose concentrations are not maintained in plasma. In conclusion, β-carotene is primarily transported
in the plasma in LDL, but its incorporation by the liver into lipoproteins does not appear to be enhanced. |
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