Abstract
The intake of γ-tocopherol by North Americans is generally higher than that of α-tocopherol. However, the levels of α-tocopherol in human blood have consistently been shown to be higher than those of γ-tocopherol suggesting differential cellular retention of the two tocopherol forms. We sought to resolve this question by studying tocopherol metabolism by human endothelial cells in culture. The time- and dose-dependent uptake of γ-tocopherol by endothelial cells was similar to that of α-tocopherol. To determine the comparative uptake between α- and γ-tocopherol, we adopted two approaches in which cells were enriched with either increasing concentrations of an equimolar mixture of α- and γ-tocopherol; or cells were enriched with a fixed concentration of tocopherols in which the α to γ ratio was varied. Our results indicated that there was a preferential uptake of γ-tocopherol by the cells. When cells were enriched with either α- or γ-tocopherol and the disappearance of individual tocopherols was monitored over time, γ-tocopherol exhibited a faster rate of disappearance. The faster turnover of γ-tocopherol can explain the discrepancy between high intake and low retention of γ-tocopherol in man.
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Abbreviations
- BSA:
-
bovine serum albumin
- EDTA:
-
ethylenediamine-tetraacetic acid disodium dihydrate
- HEPES:
-
4-(2-hydroxyethyl)-1-piperazine-ethanesulfonic acid
- HPLC:
-
high-performance liquid chromatography
- UV:
-
ultraviolet
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Tran, K., Chan, A.C. Comparative uptake of α- and γ-tocopherol by human endothelial cells. Lipids 27, 38–41 (1992). https://doi.org/10.1007/BF02537056
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DOI: https://doi.org/10.1007/BF02537056