Original Contribution OXIDIZED PROTEINS AS A MARKER OF OXIDATIVE STRESS DURING CORONARY HEART SURGERY ULRICH PANTKE,* THOMAS VOLK,* MARTIN SCHMUTZLER,* WOLFGANG J. KOX,* NICOLLE SITTE, ² and TILMAN GRUNE ² *Clinics of Anaesthesiology and Operative Intensive Medicine and ² Clinics of Physical Medicine and Rehabilitation, Medical Faculty Charite ´, Humboldt University Berlin, Berlin, Germany (Received 17 May 1999; Revised 28 June 1999; Accepted 29 June 1999) Abstract—The measurement of the degree of oxidative stress in patients often causes problems because of the lack of useful parameters. Therefore, we used an ELISA technique to evaluate serum protein carbonyls as a parameter of oxidative stress in patients during coronary heart surgery. Protein carbonyls were detected in serum samples of 14 patients undergoing coronary surgery and cardiopulmonary artery bypass grafting. A clear 2- to 3-fold increase in protein carbonyls in serum samples taken from human venous coronary sinus could be detected in the reperfusion period of the heart. We compared these data with markers of oxidative stress previously used, such as the glutathione status and the lipid peroxidation product malondialdehyde (MDA). Strong correlations of the protein carbonyl formation with MDA ( r 2 = 0.86) and oxidized glutathione ( r 2 = 0.81) were found in the early reperfusion stage. Increased levels of oxidized glutathione and MDA were detected only in the early reperfusion period. In contrast, the serum protein carbonyl content remained elevated for several hours, indicating a considerably slower serum clearance of oxidized proteins compared with that of lipid peroxidation products and the normalization of the glutathione status. We therefore concluded that the measurement of serum carbonyls by this ELISA technique is suitable to detect oxidative stress in serum samples of patients. The relative stability of the parameter makes the protein carbonyl detection even more valuable for clinical purposes. © 1999 Elsevier Science Inc. Keywords—Coronary surgery, Oxidative stress, Ischemia reperfusion, Protein carbonyls, Glutathione, Malondialde- hyde, Free radicals INTRODUCTION Reactive oxygen species seem to play a major role in the pathophysiology of ischemia reperfusion-related pro- cesses of the heart [1– 4]. Patients undergoing conven- tional coronary surgery are subjected to controlled isch- emia followed by a reperfusion period. An increase in oxidative stress during the reperfusion period may con- tribute to myocardial stunning and diverse arrhythmias [5]. Therefore, it seems important to evaluate the oxida- tive stress status of patients at different stages of the disease and also during the surgical operation. Numerous investigations were performed to measure oxidative stress–related biochemical changes during ischemia reperfusion of the heart [1– 4]. These studies suggest strongly the occurrence of oxidative stress during the early reperfusion of the heart [6 –11]. Unfortunately, most of the parameters and techniques used to measure oxidative stress are only suitable in experimental models, like the usage of spin traps [12,13], or compounds have a very short half-life, such as lipid peroxidation products, for example, 4-hydroxynonenal [14 –16] or MDA [17]. The frequently used measurement of the blood glutathi- one status is influenced by the metabolism of the red blood cell and the transport of the reduced and oxidized glutathione within various tissues. We decided to use a relatively new technique to evaluate the accumulation of oxidized proteins in serum during cardiovasculary surgery. Therefore, we used an enzyme-linked immunosorbent assay (ELISA) method previously published by Buss et al. [18]. This ELISA Address correspondence to: Tilman Grune, Clinics of Physical Med- icine and Rehabilitation, Medical Faculty Charite ´, Humboldt Univer- sity Berlin, Schumannstr. 20/21, D-10098 Berlin, Germany; Tel.: +49 (30) 2093-7514; Fax: +49 (30) 2093-7204; E-Mail: tilman.grune@charite.de. Free Radical Biology & Medicine, Vol. 27, Nos. 9/10, pp. 1080 –1086, 1999 Copyright © 1999 Elsevier Science Inc. Printed in the USA. All rights reserved 0891-5849/99/$–see front matter PII S0891-5849(99)00144-6 1080