Comet Assay in Evaluating DNA Damage Associated With Ischaemia-Reperfusion Injury in Patients Undergoing Coronary Surgery

Abstract

Ischaemia-reperfusion (I/R) injury is responsible for a number of conditions such as coronary bypass and myocardial infarction, and deaths. Oxygen-free radicals formed during I/R have been proposed as the leading causes of tissue injury, and they play an important role in I/R injury. I/R induces oxidative DNA damage (such as purinic and pyrimidinic base lesions). Comet assay is a suitable and sensitive method for early detection of low-level DNA damage. We used modifi ed alkaline comet assay in peripheral blood lymphocytes and evaluated I/R-induced DNA damage in patients undergoing coronary artery bypass graft (CABG) operation (in vivo model for I/R). No statistically signifi cant difference in DNA damage levels was found before surgery, after anaesthesia, ischemia, reperfusion, and surgery. However, blood lactate levels (assessed in parallel with the comet assay) increased after I/R and did not return to the baseline level. Our fi ndings showed that I/R injury did not induce DNA damage, but increased the lactate levels. This fi nding suggests that there might be reversible and uncommon necrosis that did not refl ect on overall DNA base damage. Further studies are needed using this approach.