Abstract: Objective To study the protective effect of sufentanil preconditioning against myocardial ischemia-reperfusion (I/R)
injury and the role of PI3K/Akt signaling pathway. Methods Sixty male SD rats weighing 250-350 g were randomly divided
into 5 equal groups, namely the sham-operated group, I/R group, sufentanil preconditioning group (Spc group), sufentanil
preconditioning + PI3K inhibitor group (Spc +W group), and PI3K inhibitor group (W group). Myocardial I/R model was
established by ligation of the anterior descending branch of the left coronary artery for 30 min followed by reperfusion for 120
min. Sufentanil was administered in 3 doses via the femoral vein before the occlusion, each at 1 μg/kg infused within 5 min at
a 5-min interval. In Spc +W and W groups, PI3K inhibitor wortmannin (15 μg/kg) was given intravenously 5 min before
sufentanil preconditioning and 35 min before ischemia, respectively. Heart rate and mean arterial pressure (MAP) were
continuously monitored during I/R. At the end of reperfusion, blood samples were obtained to determine plasma activation of
CK-MB and LDH. Acute infarct size was measured by triphenyltetrazolium chloride staining, and the myocardial tissues were
obtained to detect the expression of phosphorylated Akt using Western blotting. Results Phosphorylated Akt expression was
significantly up-regulated in I/R and Spc groups as compared with the sham group, and was significantly higher in Spc group
than in I/R group. After reperfusion, sufentanil preconditioning significantly decreased myocardial infarct size (P<0.01) and
lowered the levels of CK-MB (P<0.01) and LDH (P<0.01) compared with those in the I/R group. The I/R , Spc+W and W groups
showed no significant differences in myocardial infarct size or the levels of CK-MB and LDH. Conclusion The protective effect
of sufentanil preconditioning against myocardium against I/R injury in rats may involve PI3K/Akt signaling pathway
activation.