Ubiquinone and alpha-tocopherol in plasma; means of translocation or depot

Ubiquinone (UQ) and alpha-tocopherol (AT) are two highly lipophilic antioxidants which can be dissolved only in lipid layers or attached to protein structures. Analyses of both UQ and AT in whole blood and plasma demonstrate identical values, which excludes any significant allocation to blood cells. The lipoidic plasma structures constitute the plasma lipoprotein fractions of high (HDL), low (LDL), and very low (VLDL) density in addition to chylomicrons. This means by definition that blood and plasma UQ and AT values are limited if not related to the lipoidic deposit volume. UQ and AT increase linearly with free cholesterol (FC). FC has therefore been suggested to be a good marker for the deposit volume. The ratios UQ and AT over FC--normalized UQ (N-UQ) and normalized AT (N-AT)--have been computed for inter- and intraindividual comparisons. With a plasma UQ content of 1 microgram/ml (approximately 1 mumol/l) and a plasma volume of 41, UQ makes up about 15% of the total heart content or under 1% of UQ in skeletal muscle. The corresponding value for the total extracellular UQ content is less than 2%. This means that extracellular UQ has no or a very minor role as a UQ depot. The same is true for AT. However, for transportation and allocation determinations of N-UQ and N-AT are relevant. Assuming only a lipoprotein-related transportation, healthy persons have saturated plasma UQ and AT values in only 25% and 10% of the population, respectively. All patient categories studied have been found nonsaturated. VLDL plus LDL constitute some 90% of the UQ deposit volume.(ABSTRACT TRUNCATED AT 250 WORDS)