Effect of Olprinone on Ischemia-reperfusion Induced Myocardial Injury in Rats

Aims: This study investigated the effect of olprinone on ischemia-reperfusion (I/R) induced cardiac injury, and the underlying mechanism.

Main Methods: Male Sprague-Dawley rats were subjected to a 30-min coronary arterial occlusion followed by 24 h reperfusion. After the start of reperfusion, rats were respectively treated with olprinone in three different dosages (0.2, 0.6, 2 mg/kg, intraperitoneal injection, i.p./12 h). Twenty-four hours later, a mean arterial pressure (MAP) heart function analysis system was used to monitor hemodynamic parameters; TTC staining method was used to detect the myocardial infarct size; 24-hour mortality of rats was recorded; western blot was used to detect the protein expressions of Caspase-3, Bax, Bcl-2, Beclin-1 and LC3-II/LC3-I.

Results: Cardiac function in I/R group was lower than that in sham group (dp/dt max: 1348.29 ± 266.01 vs. 3333.73 ± 1258.03, -dp/dt max: 1163.23 ± 588.18 vs. 3198.93 ± 1416.00, P <  0.05), which was significantly improved by treatment with high dosage of olprinone (dp/dt max: 1348.29±266.01 vs. 2022.43±493.39, -dp/dt max: 1163.23±588.18 vs. 1784.50±418.92, P <  0.05). The percentage of myocardial infarct size in medium and high dosages of olprinone group was lower than that in I/R group (42.67 ± 2.94, 22.33 ± 3.63 vs. 63.67 ± 5.86, P <  0.05). There was no significant difference in mortality among each group within 24 h. Compared with sham group, the expression of Caspase-3 was significantly up-regulated in I/R group (3.44±0.47-fold of sham, P <  0.05), which was inhibited by medium dosage of olprinone treatment (2.00±0.52-fold of sham, P <  0.05 vs. I/R group); also, expression of Bax was increased compared with sham group (4.06±0.25-fold of sham, P <  0.05), which was markedly inhibited by all dosages of olprinone treatment (low: 2.16±0.61-fold, medium: 2.74±0.66-fold, high 1.65±0.55-fold, P <  0.05 vs. I/R group). Expression of Bcl-2 was increased after I/R (1.17±0.06-fold, P < 0.05), which was further elevated in all dosages of olprinone treatment (low: 1.62 ± 0.13-fold, medium: 1.46 ± 0.13-fold, high: 1.82 ± 0.39-fold, P <  0.05 vs. I/R group). In addition, compared with sham group, the expression of Beclin-1 was up-regulated to 1.44±0.05-fold of sham in I/R group (P <  0.05), which was further increased in low and medium dosages of olprinone group (low: 2.46±0.44-fold, medium: 2.80±0.75-fold, P <  0.05 vs. I/R group). Moreover, expression of LC3-II was elevated in low dosage of olprinone treated group (low: 4.50±0.47-fold, P <  0.05 vs. I/R group).

Conclusions: Olprinone improves the cardiac function in response to myocardial I/R injury by regulation of anti-apoptotic, pro-apoptotic. In addition, autophagic signal pathways may also play a role in olprinone's therapeutic effect.