['To test whether melatonin reduces oxidative and inflammatory biomarkers in a closed-chest porcine model of acute myocardial infarction.', 'Twenty pigs were randomized to receive a total dosage of 200 mg (0.4 mg/ml) of melatonin, or placebo immediately prior to reperfusion of a coronary artery balloon occlusion in a randomized, observer-blinded, placebo-controlled trial. We assessed high-sensitivity troponin T (hs-TnT), malondialdehyde and interleukin-1b, -6 and -10 at baseline, 30 min and 1, 2, 3 and 4 h after the start of reperfusion.', 'Seventeen pigs completed the trial. There was an increase in hs-TnT, but no significant difference between the melatonin-treated and placebo-treated groups. There were no significant differences in development of any of the circulating plasma markers between the two groups.'] Does melatonin affect oxidative/inflammatory biomarkers in a closed-chest porcine model of acute myocardial infarction?