Redox balance and cardioprotection.

Coronary artery disease is a major cause of morbidity and mortality in the Western countries. Acute myocardial infarction is a serious and often lethal consequence of coronary artery disease, resulting in contractile dysfunction and cell death. It is well known that unbalanced and high steady state levels of reactive oxygen and nitrogen species (ROS/RNS) are responsible for cytotoxicity, which in heart leads to contractile dysfunction and cell death. Pre- and post-conditioning of the myocardium are two treatment strategies that reduce contractile dysfunction and the amount of cell death considerably. Paradoxically, ROS and RNS have been identified as a part of cardioprotective signaling molecules, which are essential in pre- and post-conditioning processes. S-nitrosylation of proteins is a specific posttranslational modification that plays an important role in cardioprotection, especially within mitochondria. In fact, mitochondria are of paramount importance in either promoting or limiting ROS/RNS generation and reperfusion injury, and in triggering kinase activation by ROS/RNS signaling in cardioprotection. These organelles are also the targets of acidosis, which prevents mitochondrial transition pore opening, thus avoiding ROS-induced ROS release. Therefore, we will consider mitochondria as either targets of damage or protection from it. The origin of ROS/RNS and the cardioprotective signaling pathways involved in ROS/RNS-based pre- and post-conditioning will be explored in this article. A particular emphasis will be given to new aspects concerning the processes of S-nitrosylation in the cardioprotective scenario.