Sevoflurane Postconditioning Attenuates Hypoxia/Reoxygenation Injury of Cardiomyocytes Under High Glucose by Regulating HIF-1α/MIF/AMPK Pathway

Subject: Cardiovascular disease, as a very common and serious coexisting disease in diabetic patients, and is one of the risk factors that seriously affect the prognosis and complications of surgical patients. Previous studies have shown that sevoflurane post-conditioning (SPostC) exerts a protective effect against myocardial ischemia/reperfusion injury by HIF-1α, but the protective effect is weakened or even disappeared under hyperglycemia. This study aims to explore whether regulating the HIF-1α/MIF/AMPK signaling pathway can restore the protective effect and reveal the mechanism of SPostC on cardiomyocyte hypoxia/reoxygenation injury under high glucose conditions.

Methods: H9c2 cardiomyocytes were cultured in normal and high-concentration glucose medium to establish a hypoxia/reoxygenation (H/R) injury model of cardiomyocytes. SPostC was performed with 2.4% sevoflurane for 15 min before reoxygenation. Cell damage was determined by measuring cell viability, lactate dehydrogenase activity, and apoptosis; Testing cell energy metabolism by detecting reactive oxygen species (ROS) generation, ATP content and mitochondrial membrane potential; Analysis of the change of HIF-1α, MIF and AMPKα mRNA expression by RT-PCR. Western blotting was used to examine the expression of HIF-1α, MIF, AMPKα and p-AMPKα proteins. HIF-1α and MIF inhibitors and agonists were administered 40 min before hypoxia.

Results: 1) SPostC exerts a protective effect by increasing cell viability, reducing LDH levels and cell apoptosis under low glucose (5 μM) after undergoing H/R injury; 2) High glucose concentration (35 μM) eliminated the cardioprotective effect of SPostC, which is manifested by a significantly decrease in the protein and mRNA expression level of the HIF-1α/MIF/AMPK signaling pathway, accompanied by decreased cell viability, increased LDH levels and apoptosis, increased ROS production, decreased ATP synthesis, and decreased mitochondrial membrane potential; 3. Under high glucose (35 μM), the expression levels of HIF-1α and MIF were up-regulated by using agonists, which can significantly increase the level of p-AMPKα protein, and the cardioprotective effect of SPostC was restored.

Conclusion: The signal pathway of HIF-1α/MIF/AMPK of H9c2 cardiomyocytes may be the key point of SPostC against H/R injure. The cardioprotective of SPostC could be restored by upregulating the protein expression of HIF-1α and MIF under hyperglycemia.