Nicorandil prevents sirolimus-induced production of reactive oxygen species, endothelial dysfunction, and thrombus formation.

Sirolimus (SRL) is widely used to prevent restenosis after percutaneous coronary intervention. However, its beneficial effect is hampered by complications of thrombosis. Several studies imply that reactive oxygen species (ROS) play a critical role in endothelial dysfunction and thrombus formation. The present study investigated the protective effect of nicorandil (NIC), an anti-angina agent, on SRL-associated thrombosis. In human coronary artery endothelial cells (HCAECs), SRL stimulated ROS production, which was prevented by co-treatment with NIC. The preventive effect of NIC on ROS was abolished by 5-hydroxydecanoate but not by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one. NIC also inhibited SRL-induced up-regulation of NADPH oxidase subunit p22(phox) mRNA. Co-treatment with NIC and SRL significantly up-regulated superoxide dismutase 2. NIC treatment significantly improved SRL-induced decrease in viability of HCAECs. The functional relevance of the preventive effects of NIC on SRL-induced ROS production and impairment of endothelial viability was investigated in a mouse model of thrombosis. Pretreatment with NIC inhibited the SRL-induced acceleration of FeCl3-initiated thrombus formation and ROS production in the testicular arteries of mice. In conclusion, NIC prevented SRL-induced thrombus formation, presumably due to the reduction of ROS and to endothelial protection. The therapeutic efficacy of NIC could represent an additional option in the prevention of SRL-related thrombosis.

Nicorandil attenuates FeCl(3)-induced thrombus formation through the inhibition of reactive oxygen species production.

BACKGROUND: Although nicorandil has a number of beneficial cardiovascular actions, its effects on endothelial cells in the context of thrombosis have not been elucidated. METHODS AND RESULTS: Arterial thrombosis was induced by endothelial injury caused by FeCl(3) in the mouse testicular artery. Thrombus growth led to complete occlusion 12 min after endothelial injury in control mice. The antiplatelet agent, tirofiban, and nicorandil significantly slowed the growth of thrombi, resulting in arterial occlusion after 58 min and 55 min, respectively. In the absence of endothelial cells, nicorandil did not inhibit platelet aggregation. Diazoxide and high-dose isosorbide dinitrate both showed a similar effect to that of nicorandil. The beneficial effect of nicorandil was prevented by 5-hydroxydecanoate, but not by L-NAME. The production of reactive oxygen species by FeCl(3) treatment was measured with the specific fluorescent probe, dihydrorhodamine 123. After FeCl(3) treatment, nicorandil significantly inhibited the increase in fluorescence. In further experiments, incubation of human umbilical vein endothelial cells with nicorandil did not change the endothelial nitric oxide synthase (eNOS) mRNA levels, eNOS phosphorylation or nitrite production. CONCLUSIONS: Nicorandil attenuates FeCl(3)-induced thrombus formation in the mouse testicular artery, which suggests that it may inhibit the generation of reactive oxygen species by FeCl(3)-treated endothelial cells through activation of the mitochondrial ATP-sensitive potassium channels.