ATP-Sensitive Potassium Channels Mediate the Cardioprotective Effect of Panax notoginseng Saponins against Myocardial Ischaemia-Reperfusion Injury and Inflammatory Reaction

Inflammatory response during myocardial ischemia reperfusion injury (MIRI) is essential for cardiac healing, while excessive inflammation extends the infarction and promotes adverse cardiac remodeling. Understanding the mechanism of these uncontrolled inflammatory processes has a significant impact during the MIRI therapy. Here, we found a critical role of ATP-sensitive potassium channels (K-ATP) in the inflammatory response of MIRI and its potential mechanism and explored the effects of Panax Notoginseng Saponins (PNS) during this possess. Rats underwent 40 min ischemia by occlusion of the left anterior descending (LAD) coronary artery and 60 min of reperfusion. PNS was treated at the corresponding time point before operation; 5-hydroxydecanoate (5-HD) and glybenclamide (Gly) (or Nicorandil (Nic)) were used as pharmacological blocker (or nonselective opener) of K-ATP. Cardiac function and pathomorphology were evaluated and a set of molecular signaling experiments was tested. K-ATP current density was measured by patch-clamp. Results revealed that in MIRI, PNS pretreatment restored cardiac function, reduced infarct size, and ameliorated inflammation through K-ATP. However, inhibiting K-ATP by 5-HD and Gly significantly reversed the effects, including NLRP3 inflammasome and inflammatory mediators IL-6, MPO, TNF-alpha, and MCP-1. Moreover, PNS inhibited the phosphorylation and nuclear translocation of NF-kappa B in I/R myocardium when the K-ATP was activated. Importantly, PNS promoted the expression of subunits and activation of K-ATP. The study uncovered K-ATP served as a new potential mechanism during PNS modulating MIRI-induced inflammation and promoting injured heart recovery. The manipulation of K-ATP could be a potential therapeutic approach for MIRI and other inflammatory diseases.