Comparative sensitivities of tocopherol levels of platelets, red blood cells, and plasma for estimating vitamin E nutritional status in the rat

Abstract

The use of tocopherol levels of either platelets or red blood cells was tested as an index of tissue vitamin E status. Male Wistar rats were fed 0, 5, 10, 20, or 50 ppm of vitamin E (d-alpha-tocopheryl acetate) ad libitum for 10 wk. Over the dosage range from 0 to 20 ppm, response in tocopherol content of most tissues including platelets and red blood cells were linear. Over the whole range from 0 to 50 ppm, responses were curvilinear both directly and logarithmically for all tissues. In a comparison of reproducibility of responses of platelets, plasma and red blood cells, the variation of alpha-tocopherol content within groups fed the same diet was consistently lowest for platelets. Sensitivity (linear slope/SD) for reflecting vitamin E intake was higher for platelets than for either red blood cells or plasma. In vitro spontaneous hemolysis of red blood cells was less than 10% with 10 ppm of vitamin E, greater than 85% with 0 ppm, and was variable (2 to 78%) with 5 ppm. Lipid levels in plasma increased significantly as vitamin E was increased from 5 to 50 ppm of the diets. Over this range, levels of cholesterol and phospholipid increased 20% and levels of triglyceride increased almost 200%.

Assessment of Tocopherol Metabolism and Oxidative Stress in Familial Hypobetalipoproteinemia

“…In vitro erythrocyte-to-HDL exchange of ␣-tocopherol has been described (17 ) and might contribute to the observed reduction in erythrocyte ␣-tocopherol concentrations. Although platelet tocopherol concentrations have not been demonstrated to correlate with those in peripheral nervous tissue, platelet concentrations might better reflect dietary vitamin E intake because they are not passively influenced by lipid concentrations (18 ). Our preference, therefore, was to use platelet tocopherol concentrations to assess in vivo tocopherol transport.…”

Relative Bioactivity of Alpha- and Gamma-Tocopherol Calculated from Respiration Parameters in Rat Liver Mitochondria

“…Considering the results of the hemolysis test, the vitamin E requirement is optimally covered by the supplemented dl-Y-tocopherol whereas the equivalent amount of ¿//-a-tocopherol seems to be insufficient (table I). However, Lehmann [19] reported that an addition of only 10 mg ¿/-a-tocopherol acetate/kg diet (= 9.1 mg ¿/-a-tocopherol equivalents) is adequate to prevent several typical vitamin E deficiency symptoms. That corresponds to 1/5 of the ¿/-a-tocopherol equivalents used in our experiments.…”

“…This discrepancy can only be explained by the dif ferent fat components in the diets, fed to the animals of both experiments. While the semisynthetic triglyceride used in our experi ments contained only traces of unsaponifiable substances (see methods), the composi tion of the 'stripped' com oil used by Leh mann [19] is not given. We assume that it still contained available amounts of tocopherols as well as other unsaponifiable sub stances.…”

Plasma Phospholipid Transfer Protein Deficiency in Mice Is Associated With a Reduced Thrombotic Response to Acute Intravascular Oxidative Stress

“…26 -28 In fact, beyond total vitamin E content of the whole body, tissue levels (ie, amounts of ␣-tocopherol in biomembranes) would be more meaningful than plasma levels, and the relative distribution between blood and tissues may well determine the extent of the expected beneficial outcome. 29,30 In fact, the conclusions of most human studies were built on measurements of vitamin E concentration in plasma only, and this limitation might actually account for some of the heterogeneous observations. Interestingly, arterial injury of the common carotid artery in humans was found to be negatively associated with the vitamin E content of red blood cells, but not of plasma.…”