Elevated serum uric acid reduce heart damage in patients undergoing open-heart surgery
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Objectives: Peroxynitrite is species claimed to propagate ischemia/reperfusion damage. In this report levels of serum uric acid (UA), a peroxynitrite scavenger, are compared with creatine phosphokinase (CPK) in male patients before and after open-heart surgery in order to asses if increased levels of UA may protect heart from biochemical damage induced by peroxynitrite during the coronary by-pass grafting (CABG) intervention. Methods: 45 male patients (16 carvedilol pretreated (6.25 mg/ daily, during 6 weeks before surgery, mean age 55.3±1.7 years, range 50-71) and 29 patients without carvedilol pretreatment (mean age 58.3±1.4 years, range 47-73) underwent elective CABG were examined. Study inclusion criteria were CABG performed on two and more coronary-vessels with aortic crossclamp during 30-40 minutes. For assessment of patients objective health status before operations Euro- SCORE were used. Serum uric acid (UA) levels and creatine phosphokinase (CPK) were measured spectrophotometricaly by using a quantitative enzymatic assay. Results: Carvedilol pretreated patients had higher amount of serum UA (p<0.05) comparing to non-treated patients. During the surgical procedure patients are subjected to temporary ischemia due to transfer from corporeal to extracorporeal circulation. In this period of time the amount of UA decreased in carvedilol pretreated group (406±46 (t1) vs. 300±22 mmol/L (t2)) to the level of non-treated patients (328±14 (t1) vs. 322±18 mmol/L. Carvedilol pretreated patients and non-treated patients had the same level of CPK at the beginning of the surgical procedure (t1) (78±6 vs. 83+13 U/L) but lower increase (p<0.05) in CPK activity in carvedilol pretreated patients in respect to nontreated patients (338±46 vs. 644±103 U/L) at the end of procedure (t2). Such results suggest that open heart surgery led to elevated CPK levels, but this effect was less pronounced in patients with higher level of UA. Conclusions: Our results suggest possible role of UA in the protection from reperfusion injury. Increase of UA before surgery may be beneficial factor during CABG procedure in patients treated with carvedilol by decreasing level of peroxynitrite as one of molecular causes of reperfusion injury. Our results showed influence of UA on CPK levels at the end of surgical procedure, indicating that increased levels of UA may protect heart from biochemical damage induced by peroxynitrite during the CABG intervention.