Department of Cardiology, The Second Affiliated Hospital of Air Force Military Medical University, Xi'an, China.
Pharmacology. 2022;107(1-2):14-27. doi: 10.1159/000506814. Epub 2021 Oct 29.
Dexmedetomidine (Dex) and a number of miRNAs contribute to ischemia/reperfusion injury. We aimed to explore the role of Dex and miR-146a on myocardial cells injured by hypoxia/reoxygenation (H/R).
H9C2 cells were injured by H/R. Cell viability was tested using the cell counting kit-8. Lactate dehydrogenase (LDH) activity, superoxide dismutase (SOD) activity, and malondialdehyde (MDA) levels were determined using commercial kits. Flow cytometry was performed to determine apoptosis rate and reactive oxygen species (ROS) level. Protein and mRNA levels were assessed using Western blot and qPCR.
miR-146a expression and cell viability of H9C2 cells were downregulated under the circumstance of H/R injury. The tendency could be reversed by Dex, which could also upregulate SOD activity and decrease apoptosis, LDH activity, MDA, 78-kDa glucose-regulated protein (GRP78), and C/EBP homologous protein (CHOP) levels of H9C2 cells. GRP78, CHOP levels, and cell viability were negatively modulated by miR-146a. Dex elevated cell viability, catalase, MnSOD, and NAD(P)H dehydrogenase (NQO1) levels but suppressed apoptosis rate, GRP78, and CHOP levels by increasing miR-146a expression and downregulating ROS, phosphorylation of p38, and extracellular signal-regulated kinases 1/2 levels. By using SB203580 (SB), the p38 mitogen-activated protein kinase (MAPK) inhibitor, Dex or the inhibition of miR-146 upregulated cell viability but downregulated GRP78 and CHOP levels.
Dex might regulate miR-146a expression, which could further modulate the endoplasmic reticulum stress and oxidative stress and eventually affect the cell viability and apoptosis of myocardial cells injured by H/R via the MAPK signal pathway.
右美托咪定（Dex）和许多 miRNA 有助于缺血/再灌注损伤。我们旨在探讨 Dex 和 miR-146a 对缺氧/复氧（H/R）损伤心肌细胞的作用。
用 H/R 损伤 H9C2 细胞。使用细胞计数试剂盒-8 检测细胞活力。使用商业试剂盒测定乳酸脱氢酶（LDH）活性、超氧化物歧化酶（SOD）活性和丙二醛（MDA）水平。通过流式细胞术测定细胞凋亡率和活性氧（ROS）水平。使用 Western blot 和 qPCR 评估蛋白和 mRNA 水平。
在 H/R 损伤的情况下，miR-146a 的表达和 H9C2 细胞的活力降低。这种趋势可以通过 Dex 逆转，Dex 还可以上调 SOD 活性，降低 H9C2 细胞的凋亡率、LDH 活性、MDA、78-kDa 葡萄糖调节蛋白（GRP78）和 C/EBP 同源蛋白（CHOP）水平。miR-146a 负调节 GRP78 和 CHOP 水平。Dex 通过增加 miR-146a 的表达和下调 ROS、p38 磷酸化和细胞外信号调节激酶 1/2 水平来提高细胞活力、过氧化氢酶、MnSOD 和 NAD(P)H 脱氢酶（NQO1）水平，但抑制凋亡率、GRP78 和 CHOP 水平。通过使用 SB203580（SB），p38 丝裂原活化蛋白激酶（MAPK）抑制剂，Dex 或抑制 miR-146a 上调细胞活力，但下调 GRP78 和 CHOP 水平。
Dex 可能调节 miR-146a 的表达，通过 MAPK 信号通路进一步调节内质网应激和氧化应激，最终影响 H/R 损伤心肌细胞的细胞活力和凋亡。
