急、慢性抑制CaMKⅡ的活性对心衰小鼠心功能和心力储备的影响

Impact of acute and chronic inhibition of CaMKⅡ activity on cardiac function and cardiac reserve in heart failure mice

目的探讨急、慢性抑制钙/钙调素依赖蛋白激酶Ⅱ(CaMKⅡ)的活性对心衰小鼠心功能和心力储备的影响。方法选择24只C57BL6小鼠,随机分为假手术组、心衰模型组、CaMKⅡ急性抑制组及CaMKⅡ慢性抑制组,每组6只。假手术组只行开胸术,不行升主动脉缩窄术;其余三组均采用升主动脉缩窄术建立心衰模型。术后15 d,假手术组与心衰模型组小鼠腹腔注射0.1ml生理盐水一次,CaMKⅡ急性抑制组与CaMKⅡ慢性抑制组小鼠分别腹腔注射同样剂量的KN93(CaMKⅡ抑制剂)一次及连续1周。采用小动物超声心动图仪和左心室压力-容积导管分别测量各组小鼠基础状态下和异丙肾上腺素(ISO)后心功能和心力储备,包括左心室射血分数(LVEF)、左心室短轴缩短率(LVFS)、纵向应变(LS)、纵向应变率(LSR)、收缩末期压力容积关系(ESPVR)、左室内压最大上升速度-舒张末期左室容积关系(dp/dtmax-EDV)、每搏功-舒张末期容积关系即前负荷可补充的心室搏出功(PRSW)、左室内压最大下降速度(dp/dtmin)、左心室松弛时间常数(Tau)、舒张末期压力容积关系(EDPVR)等指标。结果与假手术组相比,心衰模型组小鼠的LVEF、LVFS、LS、LSR、ESPVR、dp/dtmax-EDV、PRSW和dp/dtmin均显著降低(P<0.05),而Tau和EDPVR显著升高(P均<0.05)。急性抑制CaMKⅡ的活性对心衰小鼠的LVEF、LVFS、LS、LSR、ESPVR、dp/dtmax-EDV和PRSW无显著影响,但能显著降低dp/dtmin(P<0.05),增大Tau和EDPVR(P均<0.05)。同时,急性抑制CaMKⅡ的活性也不能增加ISO作用后心衰小鼠的LVEF、LVFS、LS、LSR、ESPVR、dp/dtmax-EDV和PRSW值。慢性抑制CaMKⅡ的活性能显著增加心衰小鼠的LVEF、LVFS、LS、LSR、ESPVR、dp/dtmax-EDV和PRSW值(P均<0.05),但对dp/dtmin、Tau和EDPVR无显著影响。同时,慢性抑制CaMKⅡ的活性可显著增加ISO作用后心衰小鼠的LVEF、LVFS、LS、LSR、ESPVR、dp/dtmax-EDV和PRSW值(P均<0.05)。结论急性抑制CaMKⅡ的活性非但不能恢复心衰小鼠心脏收缩功能及其对ISO的反应性,还会导致舒张功能的进一步降低,而慢性抑制CaMKⅡ的活性既能显著改善心衰小鼠的心功能,又能改善心衰小鼠对ISO的反应性,即恢复其对β1肾上腺素受体的敏感性。

Objective To investigate the impact of acute and chronic inhibition of Ca-（2＋）/calmodulin-dependent kinase Ⅱ（ CaMKⅡ） activity on cardiac function and cardiac reserve in heart failure mice. Methods Twenty-four C57 BL6 mice were randomly divided sham-surgery group,heart failure model group,CaMKⅡacute inhibition group and CaMKⅡchronic inhibition group（ n = 6 each）. In sham-surgery group,thoracotomy was performed only and without ascending aorta coarctation operation. In the other three groups,the pressure load heart failure models were established by ascending aorta coarctation method. At 15-day after operation,0. 1 ml normal saline was administered by intraperitoneal injection in shamsurgery group and heart failure model group for one time,and KN93（ CaMKⅡinhibitor） of same dose was administered by intraperitoneal injection in CaMKⅡ acute inhibition group（ one time） and CaMKⅡ chronic inhibition group（ one week）,respectively. The small animal echocardiograph and left ventricular pressure-volume catheter were used to respectively detect the cardiac functions and cardiol reserve in the basic state and in the state stimulated by isoproterenol（ ISO）,including left ventricular ejection fraction（ LVEF）,left ventricular fractional shortening（ LVFS）,longitudinal strain（ LS）,longitudinal strain rate（ LSR）,end-systolic pressure-volume relation（ ESPVR）,the relationship between maximum rising speed of left intraventricular pressure and end-diastolic left ventricular volume（ dp/dtmax-EDV）,the relationship between stroke work and end-diastolic volume,namely the preload recruitable stroke work（ PRSW）,maximum descending speed of left intraventricular pressure（ dp/dtmin）,leftventricularrelaxation timeconstant（ Tau） and end-diastolic pressure-volume relation（ EDPVR）. Results Compared with sham-surgery group,LVEF,LVFS,LS,LSR,ESPVR,dp/dtmax-EDV,PRSW and dp/dtmin decreased significantly（ all P〈0. 05）,while Tau and EDPVR increased significantly in cardic failure model group mice（ all P〈0. 05）. Acute inhibition of CaMKⅡactivity didn＇ t significantly impact the levels of LVEF,LVFS,LS,LSR,ESPVR,dp/dtmax-EDV and PRSW,but can significantly decrease dp/dtmin level（ P〈0. 05） and increase Tau and EDPVR levels（ all P〈0. 05）. Meanwhile,acute inhibition of CaMKⅡ activity didn＇ t increase the levels of LVEF,LVFS,LS,LSR,ESPVR,dp/dtmax-EDV and PRSW after stimulation of ISO in heart failure mice. Chronic inhibition of CaMKⅡactivity can significantly increase the levels of LVEF,LVFS,LS,LSR,ESPVR,dp/dtmax-EDV and PRSW（ all P〈0. 05）,but didn＇t significantly impact the levels of dp/dtmin,Tau and EDPVR. Meanwhile,chronic inhibition of CaMKⅡ activity can significantly increase the levels of LVEF,LVFS,LS,LSR,ESPVR,dp/dtmax-EDV and PRSW after stimulation of ISO（ all P〈0. 05）. Conclusions The acute inhibition of CaMKⅡ activity not only dose not restore the heart systolic functions and the reactivity to ISO,but also will lead to a further reduction of diastolic functions in heart failure mice. The chronic inhibition of CaMKⅡ activity not only significantly improves cardiac functions of heart failure mice but also improves the reactivity of heart failure mice to ISO,namely,restores the mice susceptibility to β1-adrenergic receptor.