Abstract
BACKGROUND: Nicorandil (NIC) is a vasodilatory drug used to treat angina. However, its efficacy of cardioprotection in coronary microembolization (CME) is largely unknown. This study was undertaken to determine whether nicorandil pretreatment could attenuate myocardial apoptosis and improve cardiac function after CME in rats. METHODS: Forty-five rats were randomly divided into a Sham group, a CME group and a CME + NIC (NIC) group (n = 15 per group). CME was established by injecting plastic microspheres (42 µm in diameter) into the left ventricle of the rats in all of the groups except the Sham group. The NIC group received nicorandil at 3 mg/kg per day for seven days before the operation. Cardiac function was assessed by echocardiography, the expression levels of cleaved caspase-9/8/3 were detected by Western blot, microinfarction area was measured by haematoxylin-basic fuchsin picric acid staining, and myocardial apoptosis was detected by TUNEL staining. RESULTS: Compared to that in the Sham group, cardiac function in the CME group was significantly decreased (P < 0.05). However, compared to the CME group, the NIC group showed improved cardiac function (P < 0.05). The expression levels of cleaved caspase-9/8/3 protein and myocardial apoptosis were dramatically increased in the CME group compared to those in the Sham group (P < 0.05), while the NIC pretreatment group had significantly decreased expression levels of cleaved caspase-9/8/3 protein as well as a decreased apoptotic rate (P < 0.05). CONCLUSIONS: NIC pretreatment inhibited CME-induced myocardial apoptosis and improved cardiac function through blockade of the mitochondrial and death receptor-mediated apoptotic pathways.