Differences in intracellular calcium homeostasis between atrial and ventricular myocytes
Differences in intracellular calcium homeostasis between atrial and ventricular myocytes
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DOI：
10.1016/j.yjmcc.2008.11.003
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发表时间：
2009-04-01
影响因子：
5
通讯作者：
Trafford, A. W.
中科院分区：
文献类型：
--
作者：
Walden, A. P.;Dibb, K. M.;Trafford, A. W.
钙离子在心室兴奋收缩偶联中所起的作用已经得到了很好的认识，而且心房和心室肌细胞的收缩钙瞬变的时空特性也有了很大的差异。然而，到目前为止，还没有对心房细胞所采用的钙稳态机制以及这些机制与心室的比较进行系统的评估。在本研究中，我们试图确定肌浆网和肌膜机制对收缩期钙瞬变和[钙](I)衰变的部分贡献。实验是在分离自大鼠心房和心室的单个心肌细胞上进行的。在23℃下测量细胞内钙离子浓度、膜电流、肌浆网钙离子含量和细胞内钙缓冲容量。实验细胞的收缩期钙瞬变较小(251nmol.L-1比376+/-41nmol.L-1)，衰减更快(7.4nmol.L-1比5.45+/-0.3S(-1))。这主要是由于SR介导的钙摄取速率增加(k(SR)，6.88+/-0.6vs.4.57+/-0.3 S(-1))。心房细胞肌浆网钙离子含量增加289%，钙缓冲容量增加3倍(B-max 371.9+/-32.4vs.121.8+/-8mmol.L-1，P均<0.05)。
The role that Ca2+ plays in ventricular excitation contraction coupling is well defined and much is known about the marked differences in the spatiotemporal properties of the systolic Ca2+ transient between atrial and ventricular myocytes. However, to date there has been no systematic appraisal of the Ca" homeostatic mechanisms employed by atrial cells and how these compare to the ventricle. In the present study we sought to determine the fractional contributions made to the systolic Ca2+ transient and the decay of [Ca2+](i) by the sarcoplasmic reticulum and sarcolemmal mechanisms. Experiments were performed on single myocytes isolated from the atria and ventricles of the rat. Intracellular Ca2+ concentration, membrane currents, SR Ca2+ content and cellular Ca2+ buffering capacity were measured at 23 degrees C. Atrial cells had smaller systolic Ca2+ transients (251 +/- 39 vs. 376 +/- 41 nmol.L-1) that decayed more rapidly (7.4 +/- 0.6 vs. 5.45 +/- 0.3 s(-1)). This was due primarily to an increased rate of SR mediated Ca2+ uptake (k(SR), 6.88 +/- 0.6 vs. 4.57 +/- 0.3 s(-1)). SR Ca2+ content was 289% greater and Ca2+ buffering capacity was increased similar to 3-fold in atrial cells (B-max 371.9 +/- 32.4 vs. 121.8 +/- 8 mu mol.L-1, all differences P