Calcium transients in infant human atrial myocytes
Calcium transients in infant human atrial myocytes
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DOI：
10.1203/01.pdr.0000148066.34743.10
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发表时间：
2005-01-01
影响因子：
3.6
通讯作者：
Joyner, RW
中科院分区：
文献类型：
--
作者：
Wagner, MB;Wang, YG;Joyner, RW
孤立的婴儿心房细胞比成人心房细胞具有更慢的早期复极。此外，从室温电压钳研究，婴儿细胞有较低的基础L-型钙电流比成人细胞。我们假设，较慢的复极增加了婴儿心房细胞的钙瞬变。心房肌细胞酶促分离的活组织检查的人右心房附件的婴儿（3 - 8个月）患者谁正在接受心脏直视手术。细胞内钙瞬变测量荧光显微镜应用方波或动作电位波形在生理温度。在重复施加（1 Hz）100 ms持续时间的调节去极化至10 mV（从-80 mV）后，不同持续时间（Δ T; 2 - 100 ms）的测试脉冲在较短持续时间（Δ T = 2 ms时为33 +/-7%，Δ T = 25 ms时为80 +/-4%）下产生较小的瞬变（表示为最后调节脉冲的百分比）。对婴儿细胞重复施加成人或婴儿预先记录的动作电位，细胞具有降低的成人动作电位钙瞬变（婴儿动作电位的F/F-0 2.2 +/-0.4对成人动作电位的1.6 +/-0.2; n = 7; p <0.05）。婴儿细胞延迟的早期复极改变了Ca2+瞬变，这可能补偿了婴儿细胞中基础钙电流的较低可用性。我们已经证明测试脉冲持续时间和钙瞬变之间的陡峭关系表明，动作电位的早期复极相的调制可能在调制兴奋-收缩耦合中具有重要意义。
Isolated infant human atrial cells have a slower early repolarization than adult human atrial cells. In addition, from room temperature voltage-clamp studies, infant cells have lower basal L-type calcium currents than adult cells. We hypothesized that the slower repolarization increases the calcium transient of infant human atrial cells. Atrial myocytes were enzymatically dissociated from biopsies of human right atrial appendages of infant (3-8 mo) patients who were undergoing open-heart surgery. Intracellular calcium transients were measured with fluorescence microscopy with application of either square waves or action potential waveforms at physiologic temperature. After repetitive application (1 Hz) of 100-ms duration conditioning depolarizations to 10 mV (from -80 mV), a test pulse of varying duration (DeltaT; 2-100 ms) produced smaller transients (expressed as percentage of the last conditioning pulse) at shorter durations (33 +/- 7% for DeltaT = 2 ms, 80 +/- 4% for DeltaT = 25 ms). With repetitive application of either adult or infant prerecorded action potentials to infant cells, the cells had a decreased calcium transient with the adult action potential (F/F-0 2.2 +/- 0.4 for infant action potential versus 1.6 +/- 0.2 for adult action potential; n = 7; p < 0.05). The delayed early repolarization of infant cells alters the Ca2+ transient, which may compensate for the lower availability of basal calcium current in infant cells. The steep relationship that we have demonstrated between test-pulse duration and the calcium transient suggests that modulation of the early repolarization phase of the action potential may be of great significance in modulating excitation-contraction coupling.