磷酸二酯酶9型抑制剂PF-04449613对大鼠心脏正性肌力作用及其机理

Positive inotropic effect of phosphodiesterase type 9 inhibitor PF-04449613 in rats and its underlying mechanism

本文旨在研究磷酸二酯酶9型抑制剂PF-04449613对大鼠心脏正性肌力作用及其机理。采用在体双压力-容积环及离体心脏收缩力技术分析其对成年健康大鼠心脏正性肌力的作用特点;运用大鼠心肌细胞钙释放技术分析其作用机理。双压力-容积环实验表明:PF-04449613(5.5 mg/kg)显著增加大鼠搏出功、心输出量、每博输出量、收缩末期压力及射血分数(P<0.05),降低收缩末期容积、舒张末期容积及舒张末期压力(P<0.05)。PF-04449613对外周动脉血压的作用表现为增加收缩压、降低舒张压及血管阻力(P<0.05)。大鼠离体心脏灌流实验表明,PF-04449613浓度依赖性地增加离体大鼠左心室发展压(P<0.05)。以Fluo-4 AM为钙离子荧光指示剂的钙释放结果表明,PF-04449613(5μmol/L)显著增强肌浆网钙泵(sarcoplasmic reticulum Ca^(2+)-ATPase-2a,SERCA2a)介导的钙释放下降相的快成分,显著增加大鼠心肌细胞钙释放幅值(P<0.05)。PF-04449613(5μmol/L)降低肌浆网钙泄漏率(P<0.05)。以上结果提示,PF-04449613通过增加SERCA2a活性发挥其对大鼠心脏正性肌力作用。

This study aimed to explore the positive inotropic effect of phosphodiesterase type 9(PDE9)inhibitor PF-04449613 in rats and its cellular and molecular mechanisms.The heart pressure-volume loop(P-V loop)analysis was used to detect the effects of PF-04449613 on rat left ventricular pressure-volume relationship,aortic pressures and peripheral vessel resistance in healthy rats.The Langendorff perfusion of isolated rat heart was used to explore the effects of PF-04449613 on heart contractility.The cardiomyocyte sarcoplasmic reticulum(SR)Ca^(2+)transients induced by field stimulation and caffeine were used to analyze the mechanism underlying the effect of PF-04449613 using Fluo-4 AM as a Ca^(2+)indicator.The results indicated as follows:(1)PF-04449613(5.5 mg/kg,ip)significantly increased the stroke work,cardiac output,stroke volume,end-systolic pressure and ejection fraction(P<0.05),and decreased the end-systolic volume,end-diastolic volume and end-diastolic pressure(P<0.05).Meanwhile,the systolic blood pressure was increased and diastolic blood pressure and arterial elastance were decreased after PF-04449613 treatment(P<0.05).(2)PF-04449613(0.001,0.01,0.1,1μmol/L)significantly increased the left ventricular developed pressure(LVDP)in a concentration-dependent manner in vitro(P<0.05).(3)PF-04449613(5μmol/L)significantly increased the amplitude of SR Ca^(2+)transients mediated by facilitating sarcoplasmic reticulum Ca^(2+)-ATPase-2 a(SERCA2a)(P<0.05).(4)PF-04449613(5μmol/L)decreased the SR Ca^(2+)leak rate via ryanodine receptor 2(RyR2)(P<0.05).In conclusion,PF-04449613 exerted positive inotropic effect both in vivo and in vitro by enhancing SERCA2 a activity.