Research Article Prolonged Helium Postconditioning Protocols during Early Reperfusion Do Not Induce Cardioprotection in the Rat Heart In Vivo: Role of Inflammatory Cytokines

Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Postconditioning of myocardial tissue employs short cycles of ischemia or pharmacologic agents during early reperfusion. Effects of helium postconditioning protocols on infarct size and the ischemia/reperfusion-induced immune response were investigated by measurement of protein and mRNA levels of proinflammatory cytokines. Rats were anesthetized with S-ketamine (150mg/kg) and diazepam (1.5mg/kg). Regional myocardial ischemia/reperfusion was induced; additional groups inhaled 15, 30, or 60min of 70% helium during reperfusion. Fifteen minutes of helium reduced infarct size from 43 % in control to 21%, whereas 30 and 60 minutes of helium inhalation led to an infarct size of 47 % and 39%, respectively. Increased protein levels of cytokine-induced neutrophil chemoattractant (CINC-3) and interleukin-1 beta (IL-