UPTAKE OF DIETARY COENZYME-Q SUPPLEMENT IS LIMITED IN RATS

Coenzyme Q is an important mitochondrial redox component and the only endogenously produced lipid-soluble antioxidant. Its tissue concentrat ion decreases with aging and in a number of diseases; dietary suppleme ntation of this lipid would fulfill important functions by counteracti ng coenzyme a depletion. To investigate possible uptake, rats were adm inistered 12 mu mol coenzyme Q(10)/100 g body wt once daily by gastric intubation. The appearance of coenzyme Q(10) in various tissues and b lood after 6 h, 4 d or 8 d was studied. The control group of rats rece ived rapeseed-soybean oil (the vehicle in the experimental group). Lip ids were extracted with petroleum ether-methanol, and the reduced and oxidized forms of coenzyme Q(9) and Q(10) were separated and quantifie d by reversed-phase HPLC. In the plasma, the total coenzyme a concentr ation was doubled after 4 d of treatment. Coenzyme Q(10) was also,reco vered in liver homogenates, where, as in the plasma, it was largely in the reduced form. Uptake into the spleen could be to a large extent a ccounted for by the blood content of this organ. No dietary coenzyme Q (10) was recovered in the heart or kidney. The uptake in the whole bod y was 2-3% of the total dose. Coenzyme Q(10) found in the liver was lo cated mainly in the lysosomes. Dietary coenzyme Q(10) did not influenc e the endogenous biosynthesis of coenzyme Q(9). This is in contrast to dietary cholesterol, which down-regulates cholesterol biosynthesis. T he dietary coenzyme Q(10) level in the plasma decreased to similar to 50% after 4 d. These results suggest that dietary coenzyme Q(10) may p lay a role primarily in the blood and that no appreciable uptake occur s into tissues.