Paraoxonase-1 is a high-density lipoprotein-associated enzyme exhibitingparaoxonase, arylesterase and dyazoxonase activities. Previous research suggestsa correlation between decreased PON1 activity and with increased oxidative stress, inflammation, and greater atherosclerotic plaque formation, and that it therefore entails an increased risk of cardiovascular disease (15).Vnukov et al.showed that the postoperative period following CABG is associated with paraoxonase suppression, myeloperoxidase activation, and increased arginase activity, nitrite/nitrate levels, and asymmetric dimethylarginine. Those authors also suggested that endothelial dysfunction and a heightened systemic inflammatory response may also be seen (16).In the present study, PON andarylesterase were only lower in the DNS group at the second measurement, while at all other time points they were higher than in the IWBC group, although the difference was not statistically significant.This supports the results in the ADA group. In addition, higher PON at measurements before cross-clamp placement and after cross-clamp removalmay also be interpreted as showing better myocardial protection and a decreased risk of MI. This suggests that PON may be capable of use as a marker in determining cases without MI among coronary artery patients. Identifying patients with low PON values in CAD may allow these to be evaluated as potential candidates for MI and to be followed-up and treated without developing MI.