title: alpha-Tocopherol binding activity of red blood cells in smokers.
abstract: Despite high plasma levels of vitamin E, red blood cell membranes contain relatively low levels of vitamin E. This suggests the existence of a selective vitamin E uptake/regeneration system in human red blood cell membranes. alpha-Tocopherol binding sites on human red blood cells are thought to be involved in the uptake of alpha-tocopherol from the plasma. To understand the role of the uptake system we have compared the alpha-tocopherol content and binding activity of red blood cells from smokers and non-smokers. The specific binding of [3H] alpha-tocopherol to pure red blood cell preparations from smokers (n = 7, 28.4 +/- 2.8 years) was 30.6 +/- 3.2 fmoles per 3 x 10(8) red blood cells and for non-smokers (n = 17, 27.9 +/- 1.3 years) was 41.7 +/- 3.7 fmoles per 3 x 10(8) red blood cells. Thus alpha-tocopherol uptake activity was significantly lower in smokers (P = 0.05). Red blood cells from smokers contained less (1.8 +/- 0.4 micrograms/gHb) alpha-tocopherol than non-smokers (2.8 +/- 0.3 micrograms/gHb), (P < 0.05), despite plasma levels of alpha-tocopherol being similar: 12.9 +/- 0.8 microM in non-smokers vs. 12.7 +/- 0.5 microM in smokers. However, adjusting plasma alpha-tocopherol for total plasma cholesterol plus triacylglycerols showed alpha-tocopherol levels were higher (P < 0.01) in non-smokers (2.84 +/- 0.10 mumol alpha-tocopherol/ mmol [cholesterol+triacylglycerol]) than in smokers (2.36 +/- 0.11 mumol alpha-tocopherol/mmol [cholesterol+triacylglycerol]). The reduced alpha-tocopherol levels in red blood cells from smokers may be due to impairment of alpha-tocopherol uptake activity. The reduced levels of alpha-tocopherol in smokers red blood cells was not associated with any changes in cell membrane fluidity. At present it is not known whether supplementation of smokers with vitamin E would normalise the alpha-tocopherol uptake activity of red blood cells.
authors.affiliation: Rowett Research Institute, Aberdeen, Scotland, UK.
authors.forename: M C
authors.initials: MC
authors.lastname: Bellizzi
authors.forename: A K
authors.initials: AK
authors.lastname: Dutta-Roy
authors.forename: G G
authors.initials: GG
authors.lastname: Duthie
authors.forename: W P
authors.initials: WP
authors.lastname: James
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000032:analysis / Q000378:metabolism; D001205:Ascorbic Acid / Q000097:blood / Q000378:metabolism; D002784:Cholesterol / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D004910:Erythrocyte Membrane / Q000378:metabolism; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D005454:Fluorescence Polarization; D006801:Humans; D015227:Lipid Peroxidation; D008297:Male; D012907:Smoking; D014810:Vitamin E / Q000097:blood / Q000378:metabolism* / Q000493:pharmacokinetics; D019207:beta Carotene / Q000097:blood / Q000378:metabolism
chemical_list: D000975:Antioxidants; D008078:Cholesterol, LDL; D019207:beta Carotene; D014810:Vitamin E; D002784:Cholesterol; D001205:Ascorbic Acid