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

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 modified 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 significant 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 findings showed that I/R injury did not induce DNA damage, but increased the lactate levels. This finding suggests that there might be reversible and uncommon necrosis that did not reflect on overall DNA base damage. Further studies are needed using this approach. Ishemijsko-reperfuzijska (I/R) ozljeda _est je uzro _nik pobola i smrtnosti u slu _ajevima kao što su ugradnja koronarnih premosnica, infarkt miokarda i sl. Slobodni kisikovi radikali koji nastaju tijekom procesa ishemije i reperfuzije smatraju se jednim od glavnih uzro _nika oštećenja tkiva i imaju važnu ulogu u I/R ozljedama. I/R ozljede izazivaju oksidativna oštećenja u DNA (primjerice oštećenja purinskih i pirimidinskih baza). Kometni test osjetljiva je metoda koja omogućuje utvrđivanje niskih razina primarnih oštećenja u molekuli DNA. U ovom smo istraživanju primjenom kometnog testa na bijelim krvnim stanicama procjenjivali razine oštećenja u DNA nastale zbog I/R ozljeda u bolesnika podvrgnutih ugradnji premosnice koronarne arterije (in vivo model za I/R). Rezultati istraživanja upućuju na to da nema zna _ajnih razlika u razinama oštećenja DNA izmjerenim u uzorcima krvi uzimanima prije kirurškog zahvata, nakon anestezije te tijekom ishemije, reperfuzije i zahvata. Međutim, uo _eno je da su nakon I/R ozljede porasle razine laktata u serumu koje se više nisu vratile na po _etne vrijednosti. Takve vrijednosti laktata u serumu upućuju na to da tijekom I/R nastupa neobi _na i reverzibilna nekroza koja se, međutim, ne odražava na stupanj oštećenja DNA. Za objašnjenje ovih za