PKA信号通路与ryanodine受体介导的心肌肌浆网钙泄漏关系的研究

Relationship between PKA signaling pathway and sarcoplasmic reticulum calcium leakage mediated by the ryanodine receptor

目的:研究β肾上腺素激活的PKA信号通路与成年大鼠心肌细胞RyR2介导的肌浆网Ca2+泄漏之间的关系,探讨治疗心力衰竭的新方法。方法:NiCl2(5mmol/L)和毒胡萝卜素(TG,100nmol/L)分别阻断成年大鼠心室肌细胞的钠钙交换体和钙泵,胞外灌流异丙肾上腺素(ISO,1μmol/L)。采用激光扫描共聚焦显微镜记录灌流前后细胞内钙火花及[Ca2+]i的变化,并使用Ca2+通道阻断剂钌红(RR,5μmol/L)对β肾上腺素刺激作用进行逆转,进而阻断RyR2介导的肌浆网内钙泄漏。结果:ISO胞外灌流后,心肌细胞钙火花发生率和[Ca2+]i与对照组相比明显升高(n=10,P<0.05);加入RR后,心肌细胞内钙火花发生率与对照组比较显著降低(n=20,P<0.05),[Ca2+]i两组没有明显差别(n=20,P>0.05)。结论:ISO激活PKA信号通路后可诱导心肌细胞RyR2介导的钙泄漏,RR可有效地逆转这种钙泄漏。

Objective：To study the relationship between PKA signaling pathway activated by the β-adrenergic and the ryanodine receptorⅡ（RyR2）mediated calcium leak in the cardiac myocytes of adult rat and explore the new way of treating heart failure.Methods：Using the NiCl2（5 mmol/L）and thapsigargin（TG,100nmol/L）respectively to block the sodium-calcium exchanger（NCX）and SR Ca-ATPase（SERCA2）,and then perfusing Isoproterenol（ISO,1 μmol/L）within the extracellular solution to activate the PKA signaling pathway in the cardiac myocytes.Finally we employ the the sarcoplasmic reticulum（SR）Ca ^2＋ release inhibitor,ruthenium red（RR,5 μmol/L）to rev2erse the function of the ISO.The calcium sparks and[Ca^ 2＋ ]i changes were recorded by the laser scanning confocal microscope imaging system.Results：The incidence of calcium sparks and the[Ca ^2＋ ]i after perfusing ISO ignificantly increased compared with that under the control conditions（n=10,P0.05）;After perfusing RR,the incidence of calcium sparks significantly decreased compared with that of the condition without perfusing RR,（n=20,P0.05）,while the[Ca^ 2＋ ]i stopped increasing after perfusing RR and the line of[Ca ^2＋ ]i gradually became smooth.Conclusion：PKA signaling pathway activated by ISO could induce the calcium leak through RYR2 located on the SR of myocardial cell,and RR could effectively reverse such calcium leak.