Depletion of T-tubules and specific subcellular changes in sarcolemmal proteins in tachycardia-induced heart failure
Depletion of T-tubules and specific subcellular changes in sarcolemmal proteins in tachycardia-induced heart failure
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DOI：
10.1016/s0008-6363(03)00325-0
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发表时间：
2003-07-01
影响因子：
10.8
通讯作者：
Kamp, TJ
中科院分区：
文献类型：
--
作者：
Balijepalli, RC;Lokuta, AJ;Kamp, TJ
目的：T管膜网络参与了心肌细胞兴奋收缩偶联过程。心动过速引起的扩张型心肌病犬的心肌细胞显示，可与膜无关的染料di8-ANNEP接触的T管减少。本研究探讨了T管染色丧失的机制，并检测了兴奋-收缩偶联所必需的膜蛋白的亚细胞分布的变化。方法：应用荧光共聚焦显微镜和膜分离技术，利用多种肌膜和肌浆网蛋白的特异性标记物，对心动过速所致心力衰竭和非心衰的犬分离的心肌细胞进行研究。结果：表面糖蛋白、Na/K-ATPase、Na/Ca交换器和Ca(V)1.2的探针显示，在完整和通透性衰竭的心肌细胞中，T管标记显著减少，但不均匀，表明T管和相关的膜蛋白真正耗尽。膜分离研究显示，膜表面肌膜和T管肌膜富集组分的L钙通道和β-肾上腺素能受体减少，而Na/Ca交换蛋白水平升高。肌膜和肌浆网连接复合体中的膜组分对肌膜蛋白和肌浆网蛋白的密度无明显影响。结论：衰竭犬心室肌细胞表面和T管肌膜上的T小管明显减少，多种蛋白质密度发生改变，但连接复合体的蛋白质组成未受影响。这种亚细胞重塑导致了心力衰竭时异常的兴奋-收缩偶联。(C)2003年欧洲心脏病学会。爱思唯尔科学公司出版。版权所有。
Objective: The T-tubule membrane network is integrally involved in excitation-contraction coupling in ventricular myocytes. Ventricular myocytes from canine hearts with tachycardia-induced dilated cardiomyopathy exhibit a decrease in accessible T-tubules to the membrane-impermeant dye, di8-ANNEPs. The present study investigated the mechanism of loss of T-tubule staining and examined for changes in the subcellular distribution of membrane proteins essential for excitation-contraction coupling. Methods: Isolated ventricular myocytes from canine hearts with and without tachycardia-induced heart failure were studied using fluorescence confocal microscopy and membrane fractionation techniques using a variety of markers specific for sarcolemmal and sarcoplasmic reticulum proteins. Results: Probes for surface glycoproteins, Na/K ATPase, Na/Ca exchanger and Ca(v)1.2 demonstrated a prominent but heterogeneous reduction in T-tubule labeling in both intact and permeabilised failing myocytes, indicating a true depletion of T-tubules and associated membrane proteins. Membrane fractionation studies showed reductions in L-type Ca2+ channels and beta-adrenergic receptors but increased levels of Na/Ca exchanger protein in both surface sarcolemma and T-tubular sarcolemma-enriched fractions; however. the membrane fraction enriched in junctional complexes of sarcolemma and junctional sarcoplasmic reticulum demonstrated no significant changes in the density of any sarcolemmal protein or sarcoplasmic reticulum protein assayed. Conclusion: Failing canine ventricular myocytes exhibit prominent depletion of T-tubules and changes in the density of a variety of proteins in both surface and T-tubular sarcolemma but with preservation of the protein composition of junctional complexes. This subcellular remodeling contributes to abnormal excitation-contraction coupling in heart failure. (C) 2003 European Society of Cardiology. Published by Elsevier Science B.V. All rights reserved.