Fetal and postnatal development of Ca2+ transients and Ca2+ sparks in rat cardiomyocytes
Fetal and postnatal development of Ca2+ transients and Ca2+ sparks in rat cardiomyocytes
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DOI：
10.1016/s0008-6363(03)00255-4
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发表时间：
2003-06-01
影响因子：
10.8
通讯作者：
Tohse, N
中科院分区：
文献类型：
--
作者：
Seki, S;Nagashima, M;Tohse, N
目的：研究胎鼠和新生鼠心脏[Ca 2 +]（i）的时空动态变化。研究方法：使用共聚焦激光扫描显微镜和Ca 2+指示剂fluo-3，我们研究了从大鼠胎儿和新生儿新鲜分离的单个心室肌细胞中的Ca 2+瞬变和Ca 2+火花。用膜选择性染料（di-8-ANEPPS）标记T-小管。二氢吡啶受体（DHPR）和兰尼碱受体（RyR）的空间关联也通过双标记免疫荧光法进行了检查。结果：与成人心肌细胞相比，胎儿心肌细胞内Ca 2+瞬变的特点是[Ca 2 +]（i）的上升和下降较慢。应用ryanodine（1 μ M）或thapsigargin（1 μ M）后，胎儿Ca 2+瞬变的幅度降低。然而，钙火花很少检测到胎儿心肌细胞。在6-9天的新生儿期建立了频繁的钙火花点火，主要是在肌膜下区域观察。钙火花的发育变化与t-小管网络的发育一致。免疫荧光研究显示DHPR和RyR在出生后的时期，这是，然而，没有观察到在胎儿期的共定位。在成人肌细胞中，钙火花消失后，破坏的t-小管甘油孵育（840 mM）。结论：大鼠心室肌细胞的肌浆网（SR）在胚胎早期就已具有功能。然而，点燃的Ca 2+火花取决于出生后t-小管的形成和由此产生的共定位的DHPR和RyR。(C)2003年欧洲心脏病学会。由Elsevier Science B. V.出版，版权所有。
Objective: The aim of this study was to characterize the spatio-temporal dynamics of [Ca2+](i) in rat heart in the fetal and neonatal periods. Methods: Using confocal scanning laser microscopy and the Ca2+ indicator fluo-3, we investigated Ca2+ transients and Ca2+ sparks in single ventricular myocytes freshly isolated from rat fetuses and neonates. T-tubules were labeled with a membrane-selective dye (di-8-ANEPPS). Spatial association of dihydropyridine receptors (DHPR) and ryanodine receptors (RyR) was also examined by double-labeling immunofluorescence. Results: Ca2+ transients in the fetal myocytes were characterized by slower upstroke and decay of [Ca2+](i) compared to those in adult myocytes. The magnitude of fetal Ca2+ transients was decreased after application of ryanodine (1 muM) or thapsigargin (1 muM). However, Ca2+ sparks were rarely detected in the fetal myocytes. Frequent ignition of Ca2+ sparks was established in the 6-9-day neonatal period, and was predominantly observed in the subsarcolemmal region. The developmental change in Ca2+ sparks coincided with development of the t-tubule network. The immunofluorescence study revealed colocalization of DHPR and RyR in the postnatal period, which was, however, not observed in the fetal period. In the adult myocytes, Ca2+ sparks disappeared after disruption of t-tubules by glycerol incubation (840 mM). Conclusions: The sarcoplasmic reticulum (SR) of rat ventricular myocytes already functions early in the fetal period. However, ignition of Ca2+ sparks depends on postnatal t-tubule formation and resultant colocalization of DHPR and RyR. (C) 2003 European Society of Cardiology. Published by Elsevier Science B.V. All rights reserved.