心肌细胞核兰尼碱受体在大鼠压力超负荷心肌肥厚发生中的作用  

Changes of myocardial nuclear ryanodine receptors in pressure overload-induced heart hypertrophy in rat

作　　者：刘健[1] 何作云[1] 王培勇[2] 

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

出　　处：《中华心血管病杂志》2002年第3期168-171,共4页Chinese Journal of Cardiology

基　　金：国家自然科学基金资助课题 (No .3 9870 3 47和No .3 9870 3 92 )

摘　　要：目的　探讨大鼠心肌细胞核上兰尼碱受体 (ryanodinereceptor,RyR)在心肌肥厚发生中的作用和意义 ,以及蛋白激酶A(PKA)、钙调素 (CaM)、佛波酯 (PMA)和核外 [Ca2 + ]对其影响。方法　制备腹主动脉缩窄大鼠心肌肥厚模型 ,差速离心和密度梯度离心提纯心肌细胞核 ,3 H放射配基受体分析心肌细胞核膜RyR的动力学特性。结果　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 ,其细胞核RyR的最大结合 (Bmax)较对照组减少 5 7 8% (P <0 0 0 1) ,离解常数(Kd)较对照组降低 5 4 4 % (P <0 0 5 )。PKA使对照组细胞核RyR与3 H兰尼碱的结合增加 2 0 6 % (P<0 0 5 ) ,而对心肌肥厚组无显著作用 ;Ca2 + /CaM不影响其结合 ,而CaM抑制剂和内源性激活蛋白激酶C (PKC)则抑制其结合 (P <0 0 5 )。在核外 [Ca2 + ]为 10 -8～ 10 -4mol/L范围时 ,细胞核RyR与3 H兰尼碱的结合呈先升高后降低趋势 ,在核外 [Ca2 + ]为 10 -6mol/L时达最大结合。结论　心肌细胞核上存在受磷酸化调节的RyR ,压力超负荷心肌肥厚发生时 ,该受体密度下调而亲和力增加。Objective To determine dynamic characteristics of myocardial nuclear ryanodine receptors (RyR) and investigate the pathophysiologic roles of nuclear RyR in the development of overload induced cardiac hypertrophy Methods The model of hypertensive rat was established by abdominal aortic constriction Velocity and isopyknic gradient centrifugation was employed to fractionate rat myocardial nuclei The maximal binding (Bmax) and dissociating ratio (Kd) of ryanodine to the nuclear envelopes were measured by ryanodine binding assay Results Existence of RyR on myocardial nuclear envelope was proved Both Bmax and Kd of RyR decreased by 57 8% ( P <0 001) and 54 4%( P <0 05) respectively in hypertrophic myocardium compared with those in control cAMP dependent protein kinase A(PKA) stimulated the binding to ryanodine by 20 6% ( P <0 05) in the normal cardiac nuclei but not affected in hypertrophic group. Phosphorylation by calmodulin (CaM) did not change, whereas CaM inhibitor (calmidazolium) and phorbol myristate acetate (PMA) decreased the binding of nuclei to ryanodine in both groups ( P <0 05). The binding or ryanodine receptors in cardiac nuclear envelopes to ryanodine was stimulated by Ca 2+ in the range of 10 -8 10 -6 mol/L free extranuclear [Ca 2+ ], but was inhibited at higher [Ca 2+ ] Conclusion RyR exist in myocardial nuclei and they are regulated by PKA, CaM and PMA Binding sites of RyR in the nuclear envelopes were progressively decreased whereas the affinity increased during overload induced cardiac hypertrophy

关 键 词：压力超负荷心肌肥厚 心肌细胞 兰尼碱受体 钙释放通道 

分 类 号：R542.2[医药卫生—心血管疾病]