Posttreatment with dexmedetomidine aggravates LPS-induced myocardial dysfunction partly via activating cardiac endothelial α2A-AR in mice.

ABSTRACT

BACKGROUND: Dexmedetomidine (DEX) administered before or at 30 min after sepsis induction was reported to alleviate septic cardiomyopathy in experimental models. However, sepsis is a life-threatening organ dysfunction due to infection-induced dysregulated host response, whether DEX treatment in the presence of organ dysfunction affects septic cardiomyopathy is unknown. This study investigated the effect of DEX posttreatment on septic cardiomyopathy. METHODS: Male wild-type and α2A-adrenergic receptor (AR) knockout mice were exposed to lipopolysaccharide (LPS) or cecal ligation puncture (CLP), and cultured cardiac endothelial cells were used. Mouse survival, myocardial function, inflammatory response and related signaling pathways were determined. RESULTS: DEX treatment at 6, 9 h after LPS challenge significantly reduced survival rate of LPS-challenged mice, especially at 9 h. DEX administered at 9 h after LPS injection or CLP significantly reduced survival in LPS or CLP-induced sepsis in wild-type mice, but not in α2A-AR knockout mice. LPS treatment for 20 h decreased the left ventricle + dp/dt, increased myocardial interleukin (IL)-1ß and IL-6 concentrations as well as cardiac endothelial tumor necrosis factor (TNF)-α, vascular cell adhesion molecule-1 (VCAM-1) and ICAM-1 expression, which were enhanced by DEX treated at 9 h after LPS injection in wild-type mice, but not in α2A-AR knockout mice. Furthermore, DEX posttreatment increased p38 phosphorylation, c-Fos nuclear translocation and VCAM-1 expression in LPS-treated cardiac endothelial cells, which were eliminated by α2A-AR knockout or PKC inhibitor. CONCLUSIONS: DEX posttreatment aggravates LPS-induced cardiac inflammation and myocardial dysfunction, at least in part, via activating cardiac endothelial α2A-AR-mediated PKC signal pathway.