Increase of uncoupling protein-2 expression in the ischemic rat heart

Reactive oxygen species (ROS) have been suggested to play an important role in the myocardial damage induced by ischemia – reperfusion. One element believed to be activated by ROS and to contribute to the reduction of ROS production, is the uncoupling protein-2 (UCP2). The objective of this investigation was to explore the effect of myocardial ischemia reperfusion on cardiac UCP2 mRNA and protein levels. Male Wistar rats (250-300gr) were subjected to 30 min occlusion and 2 hours reperfusion of left coronary artery. The expression of UCP2 mRNA and protein in the ischemic area of left ventricle and non ischemic area from right ventricle were analyzed. The mRNA and protein expression were determined by RT-PCR and western blotting, respectively. Compared to control hearts, exposure to myocardial ischemia reperfusion caused a significant increase in UCP2 protein in the ischemic area of the left ventricle (116%±18, P<0.001), however UCP2 mRNA expression did not change significantly. Furthermore, in the non ischemic area of the right ventricle, neither protein nor mRNA levels were affected by myocardial ischemia reperfusion. We conclude that following acute myocardial ischemia reperfusion, UCP2 protein level is increased in the ischemic area of the left ventricle but not in the non ischemic area of the right ventricle, suggesting the local effect of ischemia on UCP2 protein expression. Furthermore, the discordance between mRNA and protein expression of UCP2 suggests that post transcriptional regulation of mRNA influences protein induction.