The effect of gradual reoxygenation on oxidative stress and myocardial gene expression after prolonged myocardial ischemia in a porcine model

• Published in: The Thoracic and Cardiovascular Surgeon
• Main Authors: Abdel-Rahman, U, Risteski, P, Tizi, K, Kerscher, S, Bejati, S, Zwicker, K, Scholz, M, Brandt, U, Moritz, A
• Format: Conference Proceeding
• Language: English
• Published: 22.06.2009
• ISSN: 0171-6425; 1439-1902
• DOI: 10.1055/s-0029-1191654

Objectives: Hyperoxic conditions during reperfusion may aggravate cardiac ischemia-reperfusion injury due to oxidative stress. In an experimental in-vivo study the cardioprotective role of gradual reoxygenation during initial reperfusion was assessed. Methods: Twenty-one adult pigs were put on cardiopulmonary bypass (CPB) with prolonged aortic cross-clamping (90min) and cardioplegic arrest. During reperfusion, ten pigs underwent standard hyperoxic reoxygenation (HR, paO2 250–350mmHg) whereas gradual reoxygenation (GR, paO2 40–90mmHg) was performed in eleven pigs. Oxidative stress was assessed by detection of oxygen radicals using electron paramagnetic resonance (EPR) spectroscopy as well as by neutrophil oxidative burst assays of the coronary sinus blood (CS) after aortic declamping. Quantitative real time PCR was used for determining myocardial gene expression (hypoxia inducible factor 1α (HIF1α), superoxide dismutase 2 (SOD2)). Results: During early reperfusion, oxygen radical production in CS blood as shown by EPR spectroscopy was significantly decreased in the GR group compared to the HR group (p<0.05). The oxidative burst of neutrophil leukocytes was significantly reduced after HR (p<0.05). Quantitative real time PCR revealed a more pronounced increase in myocardial HIF1α expression after GR versus HR (p<0.05). Expression of SOD2 was increased only in the HR group. Conclusion: Gradual reoxygenation at the onset of reperfusion limits myocardial oxidative stress in a pig model and plays an important role in terms of cardioprotection. Further studies have to define optimal reperfusion conditions.