Combined morphine and limb remote ischemic postconditioning provides an enhanced protection against myocardial ischemia/reperfusion injury

Abstract

Objective To determine whether combined morphine and limb remote ischemic postconditioning could provide an enhanced protection against myocardial ischemia/reperfusion injury. Methods Using rat in vivo myocardio ischemia/reperfusion injury(I/RI) model, sixty male SD rats were allocated into six groups(n=10) by random number method: control group (group sham), ischema/reperfusion(I/R) group(group I/R), ischemic preconditioning group(group IPC), remote ischemic postconditioning group(group RIP), morphine postconditioning group(group M), and combined morphine and remote ischemic postconditioning groups (group M+ RIP). Arrhythmias were monitored continuously during the experiment and scored in early I/R period. Serum creatine kinase MB(CK-MB) and cardiac troponin I(cTnI) levels were assayed. The infarction area was determined by Evans blue and triphenyltetrazolium chloride(TTC) staining method. Results The infarction area was (56.0±9.1)%, (23.9±5.5)%, (40.4±11.1)%, (47.7±9.3)% and (27.2±6.7)% in the I/R, IPC, RIP, M and M+RIP groups, respectively. The infarction area, serum CK-MB, cTnI level, incidence and score of arrhythmias during early reperfusion period were significantly reduced in group M+RIP compared to group I/R(P 0.05). Conclusions This experiment demonstrates that combined morphine and limb remote ischemic postconditioning provides an enhanced protection against myocardial I/RI which is comparable to ischemic preconditioning. Key words: Ischemia/reperfusion injury; Ischemic postconditioning; Limb remote ischemic; Morphine; Myocardial protection