Restricted Uptake of Dietary Coenzyme Q Is in Contrast to the Unrestricted Uptake of α-Tocopherol into Rat Organs and Cells

Abstract

The dietary uptake of α-tocopherol and coenzyme Q was investigated in rats. Rats were fed diets supplemented with α-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 α-tocopherol, but in plasma, the ratio was reversed. Among the subcellular fractions of rat liver homogenate, Golgi vesicles and lysosomes had the highest α-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 α-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 α-tocopherol exhibited a more general cellular distribution. The decay of the supplied α-tocopherol was slow in the various organs, but the disappearance of coenzyme Q was rapid from both liver and plasma. Pretreatment of rats with α-tocopherol increased the levels of both endogenous and exogenous coenzyme Q in the liver and plasma. These results demonstrate that the uptake of α-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.