UBIQUINOL UBIQUINONE RATIO AS MARKER OF OXIDATIVE STRESS IN CORONARY-ARTERY DISEASE/

The purpose of the study was to investigate changes in serum ubiquinol /ubiquinone ratio with copper ion induced oxidative stress, and to ass ess the ubiquinol/ubiquinone ratio as marker of in vivo oxidative stre ss in patients with coronary artery disease (CAD). Plasma ubiquinol, u biquinone, vitamin E (alpha-tocopherol) and total cholesterol (TC) con centrations were measured in 40 patients with angiographically confirm ed coronary artery disease and 100 apparently healthy controls. The me an (SD) ubiquinol/ubiquinone ratio of 26.5 (7.5) of the CAD patients w as significantly lower than the mean ratio of 30.2 (8.8) of the contro ls (p = 0.02). Our results indicate that the ubiquinol/ubiquinone rati o is a sensitive marker of oxidative stress and that an altered ubiqui nol/ubiquinone ratio is the first sign of lipoprotein exposure to oxid ative stress. The altered ratio in CAD patients cannot be explained by differences in plasma vitamin E levels. The vitamin E concentrations were in fact significantly higher in CAD patients, and did not appear to protect the ubiquinol from increased oxidation due to free radical reactions. These results may indicate that circulating lipoproteins of CAD patients are more exposed to, or are more susceptible to, free ra dical reactions compared with apparently healthy controls.