No abstract

The search for novel drugs for the treatment of acute myocardial infarction and reperfusion injury of the heart is an urgent aim of modern pharmacology. Opioid peptides could be such potential drugs in this area. However, the molecular mechanism of the infarct-limiting effect of opioids in reperfusion remains unexplored. The objective of this research was to study the signaling mechanisms of the cardioprotective effect of deltorphin II in reperfusion. Rats were subjected to coronary artery occlusion (45 min) and reperfusion (2 h). The ratio of infarct size/area at risk was determined. This study indicated that the cardioprotective effect of deltorphin II in reperfusion is mediated via the activation of peripheral δ2 opioid receptor (OR), which is most likely localized in cardiomyocytes. We studied the role of guanylyl cyclase, protein kinase Cδ (PKCδ), phosphatidylinositol-3-kinase (PI3-kinase), extracellular signal-regulated kinase-1/2 (ERK1/2-kinase), ATP-sensitive K+-channels (KATP channels), mitochondrial permeability transition pore (MPTP), NO synthase (NOS), protein kinase A (PKA), Janus 2 kinase, AMP-activated protein kinase (AMPK), the large conductance calcium-activated potassium channel (BKCa-channel), reactive oxygen species (ROS) in the cardioprotective effect of deltorphin II. The infarct-reducing effect of deltorphin II appeared to be mediated via the activation of PKCδ, PI3-kinase, ERK1/2-kinase, sarcolemmal KATP channel opening, and MPTP closing.

Remote postconditioning (RPost) has a great therapeutic potential for protecting the myocardium during ischemiareperfusion in clinical practice. At the same time, an important problem limiting the use of conditioning effects in the clinic is the presence of metabolic disorders in the patient. The aim of this work was to assess the effect of induced metabolic syndrome (iMetS) on the efficacy of the infarct-limiting effect of remote ischemic postconditioning (RPost) in rats and to study the mechanisms of this effect.The study was carried out on Wistar rats. MetS was induced by high-carbohydrate high-fat diet. Criteria of metabolic syndrome were an increase in the weight of animals, abdominal fat volume, the development of arterial hypertension, hypercholesterolemia, an increase in triglycerides in serum, hyperleptinemia, hyperglycemia, the development of a state of insulin resistance by a significant increase in the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) index and glucose tolerance. All animals were subjected to 45 min coronary occlusion and 120 min reperfusion.RPost led to a twofold reduction of infarct size in rats with intact metabolism (р < 0.0001), while in rats with iMetS a decrease in infarct size during RPost was 25 % (p = 0.00003), which was significantly lower than in animals without iMetC (р < 0.0001). A direct correlation was found between of infarct size during RPost and the serum leptin level of rats with iMetC.The presented data suggested that a decrease in the efficiency of remote postconditioning in rats with diet-induced metabolic syndrome depends on leptin content in blood.