INDEXES OF OXIDATIVE STRESS IN URINE OF PATIENTS UNDERGOING CORONARY-ARTERY BYPASS-GRAFTING

Indices of oxidative stress in urine were measured in twenty patients undergoing elective coronary artery bypass grafting. Hypoxanthine, xan thine and uric acid were measured in urine, as markers of ischaemia to gether with malondialdehyde, which is a marker for lipid peroxidation. To correct for renal dysfunction during coronary artery bypass grafti ng the creatinine concentration was measured in urine and plasma. The creatinine concentration in plasma increases significantly during surg ery, from 84 +/- 23 mu mol/l to 133 +/- 52 mu mol/l, whereas the creat inine concentration in urine decreases significantly, from 8.29 +/- 4. 45 mmol/l to 2.70 +/- 1.01 mmol/l, during reperfusion. For reasons of comparison, the values of the observed measurements in urine are expre ssed per mol creatinine. The hypoxanthine and xanthine excretions both increase significantly, from 15.0 +/- 7.3 and 10.9 +/- 5.7 mmol/mol c reatinine, respectively, after induction of anaesthesia to a maximum o f 33.1 +/- 16.7 and 17.4 +/- 11.1 mmol/mol creatinine, respectively, d uring reperfusion. The malondialdehyde excretion increases significant ly, from 1.38 +/- 0.80 mmol/mol creatinine after induction of anaesthe sia to a maximum of 3.87 +/- 1.87 mmol/mol creatinine during reperfusi on. The purines and malondialdehyde in urine (expressed as a ratio of creatinine), increase during coronary artery bypass grafting as a cons equence of oxygen mediated tissue injury.