Ca2+ sparks and cellular distribution of ryanodine receptors in developing cardiomyocytes from rat.
Ca2+ sparks and cellular distribution of ryanodine receptors in developing cardiomyocytes from rat.
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大鼠发育中心肌细胞中的 Ca2 火花和兰尼碱受体的细胞分布。
DOI：
10.1016/j.yjmcc.2008.03.015
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发表时间：
2008
影响因子：
5
通讯作者：
Mejía-Alvarez,Rafael
中科院分区：
文献类型：
--
作者：
Snopko,RoseM;Ramos-Franco,Josefina;DiMaio,Alessandro;Karko,KimberlyL;Manley,Christopher;Piedras-Rentería,Erika;Mejía-Alvarez,Rafael
尽管新生大鼠心肌细胞中存在丰富的Ryanodine受体（RyR），尽管RyR的单通道特性已经成熟，但RyR对兴奋-收缩（E-C）偶联的贡献很小。RyRs在肌浆网的Ca 2+释放位点和/或远离肌膜Ca 2+信号的RyRs位置的不成熟排列可以解释这种静止。因此，在NB心肌细胞中研究了Ca 2+火花及其细胞分布，并与二分体和横（T）小管的形成相关。在从成年和NB大鼠（0-9日龄）急性分离的Fluo-4负载的完整心室肌细胞中记录Ca 2+火花。在电池的中心和外围定义/比较火花。RyR与二氢吡啶受体（DHPR）的共免疫定位用于估计二联体形成，而T小管的发育使用di-8-ANEPPS和diIC 12进行研究。结果表明，NB细胞内Ca ~（2+）火花的幅度（1.7± 0.5vs.3.6 ± 1.7F/F0）、持续时间（47± 3.2vs.54.1 ±3 ms）和宽度（1.7± 0.8vs.1.2 ±0.4 μm）均低于成人。尽管总体频率未观察到显著变化，但中央火花从0-1天的约60%增加到7-9天的82%。虽然免疫定位显示在7-8天有许多中心释放位点，但质膜的荧光标记显示不太丰富的内部T小管。这可能意味着，虽然在第一周，释放位点出现与含DHPR的T小管形成二联体;这些T小管中的一些可能不连接到表面，解释了NB中E-C偶联期间的RyR静止。
Although abundant ryanodine receptors (RyRs) exist in cardiomyocytes from newborn (NB) rat and despite the maturity of their single-channel properties, the RyR contribution to excitation–contraction (E-C) coupling is minimal. Immature arrangement of RyRs in the Ca2+release site of the sarcoplasmic reticulum and/or distant RyRs location from the sarcolemmal Ca2+signal could explain this quiescence. Consequently, Ca2+sparks and their cellular distribution were studied in NB myocytes and correlated with the formation of dyads and transverse (T) tubules. Ca2+sparks were recorded in fluo-4-loaded intact ventricular myocytes acutely dissociated from adult and NB rats (0–9 days old). Sparks were defined/compared in the center and periphery of the cell. Co-immunolocalization of RyRs with dihydropyridine receptors (DHPR) was used to estimate dyad formation, while the development of T tubules was studied using di-8-ANEPPS and diIC12. Our results indicate that in NB cells, Ca2+sparks exhibited lower amplitude (1.7±0.5 vs. 3.6±1.7 F/F0), shorter duration (47±3.2 vs. 54.1±3 ms), and larger width (1.7±0.8 vs. 1.2±0.4 μm) than in adult. Although no significant changes were observed in the overall frequency, central sparks increased from ~60% at 0–1 day to 82% at 7–9 days. While immunolocalization revealed many central release sites at 7–8 days, fluorescence labeling of the plasma membrane showed less abundant internal T tubules. This could imply that although during the first week, release sites emerge forming dyads with DHPR-containing T tubules; some of these T tubules may not be connected to the surface, explaining the RyR quiescence during E-C coupling in NB.