外源性钙调素入核转运及其在大鼠心肌肥厚时的变化  

Regulation of calmodulin import to cardiac nuclei of rat and its alterations during overload-induced cardiac hypertrophy

作　　者：刘健[1] 刘晓莉[1] 王培勇[2] 何作云[3] 肖颖彬[1] 

机构地区：[1]第三军医大学新桥医院心外科,重庆400037 [2]第三军医大学新桥医院病理生理教研室,重庆400037 [3]第三军医大学新桥医院心内科,重庆400037

出　　处：《中华心血管病杂志》2004年第10期919-922,共4页Chinese Journal of Cardiology

基　　金：国家自然科学基金资助项目 ( 3 0 2 0 0 10 8)

摘　　要：目的　探讨大鼠心肌细胞核对外源性钙调素入核转运的调节机制及其在大鼠心肌肥厚时的变化。方法　制备腹主动脉缩窄心肌肥厚大鼠模型、差速离心提纯心肌细胞核、酶学方法测定钙 ATP酶活性、荧光分光光度计测定荧光标记钙调素向细胞核转入量。结果　离体纯化的大鼠心肌细胞核在ATP存在下 ,外源性钙调素经核孔向核内转运量具有显著钙离子浓度依赖性 ,随核外钙离子浓度的增加而递增 (P <0 0 5 )。在钙离子浓度为 10 -3 mol/L时 ,钙 ATP酶抑制剂thapsigargin (5μmol/L)、兰尼碱受体拮抗剂钌红 (rutheniumred ,5 0 μmol/L)和IP3 受体拮抗剂肝素 (10 μg/ml)使外源性钙调素的细胞核孔转运分别降低 90 %、2 0 %和 89% (P <0 0 5 )。腹主动脉缩窄术后 4周大鼠心肌显著肥厚 ,伴有明显的血流动力学异常 ,与对照组相比 ,腹主动脉缩窄心肌肥厚大鼠外源钙调素入核转运明显减少 (P <0 0 5 ) ,心肌细胞核钙 ATP酶活性显著下降 (P <0 0 0 1)。结论　外源性钙调素入核转运可能受核外钙离子浓度和核钙摄取、释放系统所调节 ,心肌肥厚时 ,钙调素入核转运减少、心肌细胞核钙 ATP酶活性下降 ,可能在相对稳定核功能紊乱的调节中起负性反馈作用。Objective To investigate the relationship between calmodulin (CaM) import to isolated card iac nuclei and nuclear calcium handling system and the alterations of CaM import during overload-induced cardiac hypertrophy in vitro. Methods Velocity and isopyknic gradient centrifugation was employed to fractionate rat myocardial nuclei. Alexa Fluor_TM 488 conjugated CaM was used as fluoresce nt probes to determine CaM import to nuclei. The cardiac hypertrophy rat model was established by abdominal aortic constriction. The alterations in Ca_2+ -ATPase activity of the cardiac nuclei were also investigated. Results Ca__2+ stimulated nuclear translocation of CaM in a concentr ation-dependent way, and CaM nuclear translocation was down regulated significa ntly by Ca_2+ ATPase inhibitor thapsigargin, and by ryanodine receptor anta gonist ruthenium red and 1,4,5- inositol triphosphate (IP 3) receptor antagoni st heparin (by 90%, 20% and 89% respectively, P<0.05). The CaM import and t he Ca_2+-ATPase activity in cardiac nuclei were decreased identically duri ng overload-induced cardiac hypertrophy (P<0.05). Conclusions _CaM did not diffuse freely through nuclear pores and import of CaM to my ocardial nuclei was mediated by the elevation of free Ca_2+ and may be regu lated by nuclear calcium handling systems. The decrease of the CaM import and th e Ca_2+-ATPase activity in cardiac nuclei may be partly responsible for th e modified cardiac function during pressure overload-induced cardiac hypertroph y. [

关 键 词：心肌肥厚 转运 大鼠 外源性 心肌细胞 钙-ATP酶 钙调素 核孔 钌红 钙离子浓度 

分 类 号：R542.2[医药卫生—心血管疾病] R541[医药卫生—内科学]