Traber M G, Diamond S R, Lane J C, Brody R I, Kayden H J
Department of Medicine, New York University School of Medicine, New York 10016.
Lipids. 1994 Oct;29(10):665-9. doi: 10.1007/BF02538909.
The purpose of this study was to investigate the temporal relationships of the transport of beta-carotene in human lipoproteins. We administered 60 mg beta-carotene with breakfast to nine fasting subjects, then blood samples were collected at intervals of up to 75 h, lipoproteins were isolated, and beta-carotene was quantitated. beta-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 beta-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 beta-carotene was compared with the results of earlier studies on the transport of stereoisomers of alpha-tocopherol. Unlike plasma RRR-alpha-tocopherol concentrations, which are maintained by the preferential incorporation of RRR-alpha-tocopherol into VLDL by the liver, beta-carotene increased and decreased in VLDL similarly to SRR-alpha-tocopherol, a stereoisomer whose concentrations are not maintained in plasma. In conclusion, beta-carotene is primarily transported in the plasma in LDL, but its incorporation by the liver into lipoproteins does not appear to be enhanced.
本研究的目的是调查β-胡萝卜素在人脂蛋白中的转运时间关系。我们给9名空腹受试者在早餐时服用60毫克β-胡萝卜素，然后每隔75小时采集血样，分离脂蛋白，并对β-胡萝卜素进行定量。乳糜微粒和极低密度脂蛋白（VLDL）中的β-胡萝卜素浓度分别在6小时和9小时达到峰值。尽管如此，在所有时间点，血浆中大部分β-胡萝卜素都存在于低密度脂蛋白（LDL）中，而高密度脂蛋白（HDL）携带的比例较小（在24小时时，LDL中为73±8%，而HDL中为23±5%）。在三名受试者中，将β-胡萝卜素的转运与早期关于α-生育酚立体异构体转运的研究结果进行了比较。与血浆RRR-α-生育酚浓度不同，RRR-α-生育酚通过肝脏优先掺入VLDL来维持，β-胡萝卜素在VLDL中的增减与SRR-α-生育酚相似，SRR-α-生育酚是一种血浆中浓度无法维持的立体异构体。总之，β-胡萝卜素主要在血浆中由LDL转运，但肝脏将其掺入脂蛋白的过程似乎并未增强。
