L-型钙通道激动剂对心肌细胞局部诱发钙释放的影响

Effects of L-type Calcium Channel Activator on Local Evoked Calcium Release in Myocardial Cells

目的:研究L-型钙通道激动剂(FPL64176)对心肌细胞局部诱发钙信号的影响特点。方法:采用非紧密封接膜片钳技术与激光扫描共聚焦显微镜钙成像技术相结合的方法,局部触发细胞内钙释放。此技术可自由控制膜去极化水平,使FPL64176只在局部发挥作用。结果:正常情况下,局部兴奋-收缩耦联概率(δSC)和平均诱发钙瞬变与膜去极化水平的关系均呈"钟形"电压-依赖特性。FPL64176作用下,δSC和局部平均诱发钙瞬变均有不同程度的增强(P<0.05);低膜电位水平下的孤立钙火花幅度也明显增大(P<0.05)。结论:"钟形"电压-依赖特性说明,本质上此兴奋-收缩耦联的机制是钙诱导钙释放,而不是由于去极化本身所致。FPL64176不影响局部细胞内钙释放的"钟形"电压-依赖特性。

Objective： To investigate the effects of L-type calcium channel activator（FPL64176）on local evoked calcium release in myocardial cells. Methods： Using loose-seal patch clamp technique combined with laser scanning confocal microscopic calcium imaging, the intraeellular calcium release was triggered locally. The membrane potential could be controlled optionally and FPL64176 could only take effect locally. Results： Under the control condition, the local excitation-contraction coupling fidelity（δSC）and averaged local evoked calcium transients were bell-shaped voltage-dependent on the membrane potentials. With FPL64176 within the pipette, δSC and averaged local evoked calcium transients were all enhanced differentially（ P 〈 0.05）. At low membrane potential, the amplitude of solitary calcium sparks increased with FPL64176（ P 〈 0.05）. Conclusion： The bell-shaped voltage-dependence shows that the local excitation-contraction is also through the mechanism of calcium-induced calcium release, but not through the membrane depolarization itself. And FPL64176 does not change this voltage-dependence.