心力衰竭鼠心脏肿瘤坏死因子α超量表达对膈肌收缩功能的影响

目的 研究心力衰竭鼠心脏肿瘤坏死因子α(TNFα)的超量表达对小鼠膈肌收缩功能的影响.方法 应用体外直接电刺激法研究野生型同窝对照小鼠和心肌特异性超量表达TNF-α心力衰竭转基因小鼠的膈肌.应用2',7'二氯荧光素乙酰乙酸盐(DCFH-DA)测定胞液氧化物水平,用荧光显微镜检测带有荧光的氧化产物.结果 转基因心力衰竭小鼠膈肌收缩力与对照组小鼠相比下降了47%,分别为(13.2±0.8)和(25.1±0.6)N/cm2,P＜0.01;膈肌收缩力减弱与细胞内氧化物水平明显升高有关(P＜0.05).使用抗氧化剂N-乙酰半胱氨酸(NAC)10 mmol/L 30 min后,膈肌收缩力得到部分恢复(P＜0.01).外源性TNFα 500μmol/L可增加对照组小鼠膈肌的氧化产物,导致膈肌收缩功能减弱,但NAC可抑制这种膈肌收缩无力.结论 心力衰竭鼠心脏TNFα超量表达引起氧化应激,导致小鼠膈肌收缩功能失调.

Abstract：

Objective To study the effect of overexpression of tumor necrosis factor-α (TNFα) in failing heart on contractile function of mouse diaphragm. Methods Diaphragms excised from transgenic mice with cardiac specific overexpression of TNF-α and from wild-type littermate controls were studied in vitro with direct electrical stimulation. Cytosolic oxidant levels were measured with 2',7'-dichlorofluorescin diacetate (DCFH-DA). Emissions of the oxidized product were detected by fluorescence microscopy. Results The diaphragm contractile force in transgenic animals with heart failure was 47% less than in controls [(13. 2±0. 8) N/cm2 vs. (25.1±0. 6) N/cm2 , P＜O. 01]. The weakness was associated with greater intracellular oxidant levels (P＜0. 05) and was partially reversed by 30-minute incubation with the antioxidant N-acetylcysteine (NAC) 10 mmol/L ( P ＜ 0. 01 ).Exogenous TNF-a 500 mmol/L increased oxidant production in diaphragm of wild-type mice and caused weakness that was inhibited by NAC. Conclusions Overexpression of TNF in failing heart causes oxidative stress which leads contractile dysfunction in mouse diaphragm.