Restricted uptake of dietary coenzyme Q is in contrast to the unrestricted uptake of alpha-tocopherol into rat organs and cells.
The dietary uptake of alpha-tocopherol and coenzyme Q was investigated in rats. Rats were fed diets supplemented with alpha-tocopherol or coenzyme Q10 (1 g/kg diet) or an unsupplemented control diet. In control rat tissues, the content of coenzyme Q was 4-11 times higher than that of alpha-tocopherol, but in plasma, the ratio was reversed. Among the subcellular fractions of rat liver homogenate, Golgi vesicles and lysosomes had the highest alpha-tocopherol concentration, and high concentrations of coenzyme Q were observed in the outer and inner mitochondrial membranes as well as in lysosomes, Golgi vesicles and plasma membranes. The uptake of alpha-tocopherol into the liver and plasma reached a maximal level after only 2 d of supplementation, whereas in the kidney, heart, muscle and brain, the levels continued to increase throughout the 6-wk treatment period. In contrast, dietary coenzyme Q was taken up into the liver and plasma only, and not into the other organs. This lipid appeared mainly in the Golgi system, whereas alpha-tocopherol exhibited a more general cellular distribution. The decay of the supplied alpha-tocopherol was slow in the various organs, but the disappearance of coenzyme Q was rapid from both liver and plasma. Pretreatment of rats with alpha-tocopherol increased the levels of both endogenous and exogenous coenzyme Q in the liver and plasma. These results demonstrate that the uptake of alpha-tocopherol from the diet is an extensive and general phenomenon at both the tissue and cellular levels, in contrast to the selective and restricted uptake of coenzyme Q.
Zhang
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Division of Medical Cell Biology, Karolinska Institutet, Huddinge, Sweden.
Turunen
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M
Appelkvist
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EL
D000818:Animals; D001692:Biological Transport / Q000502:physiology; D001921:Brain / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D006056:Golgi Apparatus / Q000737:chemistry / Q000378:metabolism; D007668:Kidney / Q000737:chemistry / Q000378:metabolism; D008099:Liver / Q000166:cytology* / Q000378:metabolism* / Q000648:ultrastructure; D008247:Lysosomes / Q000737:chemistry / Q000378:metabolism; D008297:Male; D008928:Mitochondria / Q000737:chemistry / Q000378:metabolism; D009132:Muscles / Q000737:chemistry / Q000378:metabolism; D009206:Myocardium / Q000737:chemistry / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D014451:Ubiquinone / Q000032:analysis / Q000097:blood / Q000493:pharmacokinetics*; D014810:Vitamin E / Q000032:analysis / Q000097:blood / Q000493:pharmacokinetics*
D014451:Ubiquinone; D014810:Vitamin E