Vitamin E binds to specific binding sites and enhances prostacyclin production by cultured aortic endothelial cells

M. Kunisaki, F. Umeda, T. Inoguchi, H. Nawata

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

We evaluated the effect of d-α-tocopherol (vitamin E) on the production of prostacyclin (PGI2) by cultured bovine aortic endothelial cells. Vitamin E at physiological doses significantly enhanced the production of PGI2 by aortic endothelial cells when added to the culture simultaneously with histamine, the Ca2+ ionophore A23187 (A23187), plasma-derived serum (PDS), or arachidonic acid. This effect was found to occur in a time- and dose-dependent manner, and the maximal enhancement was produced by 9.28μM of vitamin E for 1h incubations. Significantly lower amounts of lipid peroxides were measured in endothelial cells stimulated by 10% PDS with 9.28μM of vitamin E than in those stimulated without vitamin E for over 24h, although the stimulation during the initial 1 to 12h period did not have a significant effect on lipid peroxide formation in cultured aortic endothelial cells. We also demonstrated that bovine aortic endothelial cells have specific binding sites for [3H]vitamin E that exhibited time- and temperature-dependent saturability. At 4°C, the nonspecific binding was 8-12% of the total binding, and the specific binding reached equilibrium by 2h. Specific binding increased with the concentration of [3H]vitamin E and became saturated at concentrations between 1.5μM and 2.0μM per 2.0x105 cells. Raising the unlabeled vitamin E concentration from 97.7nM to 1,000μM reduced the specific binding of 2.0μM [3H]vitamin E. The Scatchard plot of [3H]vitamin E binding to the endothelial cells shows two classes of binding sites: one with a high affinity (K(a1) 2.48±0.32x107M-1, n=6) and a low capacity (n1 1.20±0.34x107 sites/cell) and the other with a low affinity (K(a2) 1.18±0.32x105M-1) and a high capacity (n2 3.39±0.53x109 sites/cell). Our results suggest that the endothelial cells binding sites for vitamin E may play some roles in vascular homeostasis in vivo, and that vitamin E may prevent the development of atherosclerotic changes due in part to the enhancement of PGI2 production by the vascular wall and its action as an antioxidant in vascular endothelial cell.

Original languageEnglish
Pages (from-to)744-751
Number of pages8
JournalThrombosis and Haemostasis
Volume68
Issue number6
DOIs
Publication statusPublished - 1992

All Science Journal Classification (ASJC) codes

  • Hematology

Fingerprint Dive into the research topics of 'Vitamin E binds to specific binding sites and enhances prostacyclin production by cultured aortic endothelial cells'. Together they form a unique fingerprint.

  • Cite this