CaMK Ⅱ途径在慢性心衰模型触发性心律失常产生中的作用

目的研究异丙肾上腺素和高频率刺激对心衰心肌细胞晚发后除极(DADs)产生的影响以及钙调蛋白激酶Ⅱ(CaMKⅡ)途径在DADs产生中的作用。方法制备家兔慢性心衰模型,酶解法分离心室肌细胞,将细胞分为正常对照组(Ctl组)、正常对照+异丙肾上腺素干预组(Ctl+ISO组)、慢性心衰组(CHF组)、慢性心衰+异丙肾上腺素干预组(CHF+ISO组)、慢性心衰+异丙肾上腺素干预+KN93干预组(KN93组)。应用全细胞膜片钳技术记录动作电位(AP),采用含1μmol/L异丙肾上腺素的正钙蒂罗德液灌流心室肌细胞,在1～2Hz电刺激下,诱发心肌细胞产生DADs。在此基础上用KN93(1μmol/L)灌流心衰心肌细胞,观察CaMKⅡ的特异抑制剂KN93对DADs发生率、DADs的幅值、联律间期和发生个数的影响。结果灌流正钙蒂罗德液,并在1Hz电刺激下,Ctl组、Ctl+ISO组、CHF组、CHF+ISO组的DADs发生率分别为15.0%(3/20)、45.0%(9/20)、26.7%(12/45)、92.3%(36/39)。以含1μmol/L异丙肾上腺素和1μmol/L KN93的蒂罗德液灌流心衰心肌细胞,在1Hz电刺激下,KN93组的DADs诱发率为50%(7/14);再给予2Hz的刺激,记录到DADs的幅值为(1.82±0.78)mV、联律间期为(524.62±390.91)ms、个数为(2.42±0.90)。结论异丙肾上腺素和高频率刺激均可诱发心衰心肌细胞DADs的产生;模型应激状态下,KN93可以抑制慢性心衰心肌细胞DADs,CaMKⅡ信号转导途径可能是慢性心衰触发性心律失常产生的重要途径。

Role of CaMKⅡ Signal Transduction Pathways in Pathogenesis of Triggered Arrhythmias in Chronic Heart Failure Model

Objective To investigate the effect of isoproterenol(ISO)and high-frequency electrical stimulation on delayed afterdepolarization(DADs)in cardiac myocytes of rabbits with chronic heart failure(CHF),and explore the role of KN93,a kind of calcium/calmodulin-dependent protein kinase(CaMKⅡ)inhibitor,in the pathogenesis of DADs.Methods The rabbit chronic heart failure models were made and single ventricular myocytes were isolated by using enzymatic dissociation method.The cardiac myocytes were divided into Ctl group,Ctl+ISO group,CHF group,CHF+ISO group,KN93 group.Action potential(AP)was recorded by using whole cell patch clamp technique.In the cardiac myocytes perfused with ISO(1 μmol/L)Tyrode’s solution,the incidence of DADs under high-frequency electrical stimulation(1-2 Hz)was monitored.Thereafter,the cells were perfused with KN93,and the impact of KN93 on incidence of DADs,amplitude,coupled interval and counts was observed.Results In the cardiac myocytes perfused with Tyrode’s solution under 1 Hz electrical stimulation,the incidence of DADs in Ctl group,Ctl+ISO group,CHF group and CHF+ISO group was 15.0%(3/20),45.0%(9/20),26.7%(12/45)and 92.3%(36/39)respectively.In the cardiac myocytes perfused with ISO(1 μmol/L)and KN93(1 μmol/L)Tyrode’s solution,the incidence of DADs in KN93 group was 50%(7/14)under 1 Hz electrical stimulation,and under 2 Hz electrical stimulation,amplitude,coupled interval and counts of DADs were(1.82±0.78)mV,(524.62±390.91)ms,and(2.42±0.90)respectively.Conclusion DADs in the cardiac myocytes of rabbit with CHF can be induced by both ISO and high-frequency electrical stimulation.KN93 can suppress DADs in CHF under stress.CaMKⅡ signal transduction pathways may be involved in the pathogenesis of triggered arrhythmias in CHF.