Intravenous nicorandil preserves endothelial junctions by decreasing endothelin-1 via activation of ATP-sensitive K⁺ channel

BACKGROUND: It has been verified that nicorandil can attenuate myocardial no-reflow. However; the effects of nicorandil on endothelial junctions and Endothelin-1 (ET-1) are unknown. METHODS: 40 mini-swines randomized into 5 study groups: 8 in control, 8 nicorandil pretreatment, 8 in glibenclamide (KATP channel blocker)-treated, 8 in nicorandil and glibenclamide-pretreated and 8 in sham-operated. Acute myocardial infarction and reperfusion model was created with three-hour occlusion of the left anterior descending coronary artery followed by one-hour reperfusion. RESULTS: In control group, plasma ET-1 significantly increased, ET-1 or VE-cadherin level in the reflow and no-reflow myocardium was significantly higher or lower than that in normal myocardium. Compared with the control group, nicorandil significantly decreased plasma ET-1 and myocardial tissue ET-1, maintained VE-cadherin level. However, glibenclamide abrogated the protective effect of nicorandil. CONCLUSIONS: The beneficial effect of nicorandil on endothelial junctions could be due to its effect on ET-1 via the activation of KATp channel.