Soad A. A. Selim, Salah M. Zaghloul, Nawal Kh. Gerges and Ahmad Al-Sayed
Background: Irisin, a newly identified myokine, is critical in modulating body metabolism, thermogenesis and reducing oxidative stresses. Lower plasma level of irisin in patients with acute myocardial infarction (AMI) was reported. Nevertheless, the significance and functional role of irisin in the modulation of myocardial ischemia and reperfusion injury are not clear. Objective: This study was designed to explore possible effect of irisin on ischemia-reperfusion injury in isolated heart of adult male albino rats and to explain the possible involved mechanisms, in a trial to clarify irisin expected cardioprotective effect. Design: This study was carried out on thirty sex adult male albino rats which were divided equally (n=12) into 3 groups: Group I (ischemia-reperfusion I/R group); hearts were stabilized then subjected to (I/R) protocol, Group II (Irisin pre-conditioning group); Irisin was infused for 20 minutes before hearts were subjected to ischemia and Group III (Irisin post-conditioning group); Irisin was infused for 20 minutes at the beginning of 60 minutes of reperfusion. Cardiac performance indicators as left ventricular pressure (LVP), +max (LV dp/dt), -max (LVdP/dt), in addition to heart rate were recorded. Lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB), superoxide dismutase (SOD) and C-reactive protein (CRP) were measured in the collected perfusate and cardiac Malondialdehyde (MDA) was measured. Finally, Nitro blue tetrazolium stain was used to detect the necrotic tissue percentage to the whole left ventricular mass. Results: In group III (post conditioning group), there was a significant increase of the studied cardiac parameters compared to group I (I/R). Irisin significantly increased LVP, +max (dp/dt), -max (dp/dt) and HR in comparison with I/R group. This was associated with a significant decrease in LDH and CK-MB levels, a significant increase in SOD level and a significant decrease in MDA and CRP levels. Moreover, Irisin caused a significant decrease in percentage of necrotic tissue to the whole left ventricular mass. Regarding group II, no significant changes were detected in all parameters when compared to group I. Conclusion: Irisin could protect against ischemia/ reperfusion injury in vitro through its antioxidant and anti-inflammatory properties, by limiting the infarction area, only if given as a post conditioning factor after I/R. Those results open the way to include Irisin among the strategies for management of cardiac infarction during reperfusion.
Irisin; Myokines; MI; Heart; Cardioprotection; Ischemia/Reperfusion