苍术素对大鼠心脏正性肌力的作用及其机制

Positive inotropic effect of atractylodin in normal rats and its underlying mechanism

目的:研究中药苍术的有效成分苍术素(Atractylodin)的正性肌力作用及其机理。方法:随机选取6只雄性SD大鼠进行在体压力-容积环(P-V loop)实验,加药前为Control组,经腹腔注射苍术素(3 mg/kg)后为苍术素组(自身对照),分析6只雄性大鼠加药后对大鼠左心室心输出量、容积及动脉压的作用;大鼠离体心脏灌流实验中,依次灌流给药:第一部分为Control→0.1→1→10μmol/L苍术素浓度梯度灌流,第二部分为Control→200 nmol/L H89(PKA抑制剂)→200 nmol/L H89+10μmol/L苍术素,第三部分为Control→500 nmol/L KN-93(CaMKII抑制剂)→500 nmol/L KN-93+10μmol/L苍术素,第四部分为Control→10 nmol/L Calyculin A(PP1,PP2A抑制剂)→10 nmol/L Calyculin A+10μmol/L苍术素,加药前的正常空白组为Control组,分析每部分各6只雄性大鼠的组间左心室发展压的变化;在大鼠心肌细胞钙释放实验中,分组、给药的方法和浓度同离体心脏实验,分析来源于6个雄性大鼠6个左心室心肌细胞组间钙释放幅值的变化。结果:①P-V loop实验表明:与Control组相比,苍术素组(3 mg/kg)腹腔注射30 min后,显著增加大鼠心输出量、搏出功及心率(P<0.05),降低动脉舒张压(P<0.05),而对收缩压无明显影响;②离体心脏实验表明:与Control组相比,苍术素组(0.1,1,10μmol/L)灌流10 min后,能显著增加大鼠离体心脏左心室发展压(LVDP)(P<0.05),其作用能被H89组(200 nmol/L)所阻断;③心肌细胞钙释放实验表明:与Control组相比,苍术素组(10μmol/L)灌流10 min后,基于肌浆网钙泵(SERCA2a)显著增加大鼠心肌细胞钙释放幅值(P<0.05),其作用能被H89组(200 nmol/L)所阻断。结论:苍术素具有正性肌力作用,其血流动力学特点表现为降低在体大鼠动脉舒张压而不增加收缩压,苍术素的正性肌力作用机制是通过PKA-SERCA2a通路发挥的。

Objective:To explore the positive inotropic effect of atractylodin which is major active component of Rhzoma Atractylodis Lanceae and its underlying mechanism.Methods:For in vivo study,six male SD rats were randomly selected for the heart pressure-volume loop(P-V loop)experiment.The effects of atractylodin(3 mg/kg,intraperitoneal injection)on hemodynamic parameters such as LVDP(left ventricular developed pressure),SW(stroke work),HR(heart rate),CO(cardiac output),SBP(systolic blood pressure)and DBP(diastolic blood pressure)were analyzed.For in vitro study,left ventricular developed pressure(LVDP)from the Langendroff-perfused isolated rat heart was analyzed before as the control and after atractylodin perfusion.For in vitro study,the effects of atractylodin and atractylodin with H89(PKA inhibitor)or KN-93(CaMKII inhibitor or Calyculin A(PP1,PP2A inhibitor)on LVDP were analyzed.The experiments were separated into four parts with six isolated hearts for each as follows:(1)Control→0.1→1→10μmol/L atractylodin;(2)Control→200 nmol/L H89(PKA inhibitor)→200 nmol/L H89+10μmol/L atractylodin;(3)Control→500 nmol/L KN-93(CaMKII inhibitor)→500 nmol/L KN-93+10μmol/L atractylodin;(4)Control→10 nmol/L Calyculin A(PP1,PP2A inhibitor)→10 nmol/L Calyculin A+10μmol/L atractylodin.For the study of rat left ventricular myocyte Ca 2+transient induced by field stimulation,the experiment design was the same as in vitro study.The six cells from the different rats were used for each part experiment.Results:①Atractylodin(3 mg/kg)significantly increased the heart rate,cardiac output and stroke work(P<0.05)and decreased the diastolic blood pressure(P<0.05).②Atractylodin(0.1,1,10μmol/L)significantly increased the LVDP in a concentration dependent manner(P<0.05).The positive inotropic effect of atractylodin could be blocked by PKA inhibitor H89.③Atractylodin(10μmol/L)significantly increased the amplitude of SR Ca 2+transient amplitude mediated by facilitating sarcoplasmic reticulum SERCA2a.The enhanced amplitude of SR Ca 2+transient could be blocked by PKA inhibitor H89.Conclusion:Atractylodin had positive inotropic effect in rat heart both in vivo and in vitro with decreased diastolic blood pressure and its underlying mechanism was mediated by PKA.Based on the fact that the atractylodin exerted its positive inotropic effect was mediated by PKA,the PKA-SERCA2a signaling pathway might be the mechanism of the atractylodin's positive inotropy.