High-Resolution Optical Measurement of Cardiac Restitution, Contraction, and Fibrillation Dynamics in Beating vs. Blebbistatin-Uncoupled Isolated Rabbit Hearts
High-Resolution Optical Measurement of Cardiac Restitution, Contraction, and Fibrillation Dynamics in Beating vs. Blebbistatin-Uncoupled Isolated Rabbit Hearts
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DOI：
10.3389/fphys.2020.00464
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发表时间：
2020-05-26
影响因子：
4
通讯作者：
Christoph, Jan
中科院分区：
文献类型：
--
作者：
Kappadan, Vineesh;Telele, Saba;Christoph, Jan
光学标测是一种高分辨率荧光成像技术，使用电压或钙敏感染料来可视化心脏表面的电激发波。然而，光学标测对心脏组织的运动非常敏感，这导致荧光信号中的所谓运动伪影。为了避免运动伪影，通常使用药理学兴奋-收缩解偶联剂（诸如Blebbistatin）来抑制心肌的收缩。然而，药物的使用可能会影响心脏电生理学。最近，它已被证明，数值运动跟踪可以显着减少光学标测中的运动相关的伪影，使心脏电生理和力学的同时光学测量。在这里，我们结合联合收割机比率光学映射与数值运动跟踪，以进一步提高这些测量的鲁棒性和准确性。我们通过成像和比较收缩、非工作与Blebbistatin-arrested Langendorff灌注兔心脏（N = 10）中的心脏恢复和室颤（VF）动力学来评估该方法的性能。我们发现，与未与Blebbistatin偶联的心脏相比，收缩心脏的动作电位时程（APD）平均短25 ± 5%。APD的相对缩短被认为是在较高的频率较大。发现VF在收缩心脏中显著加速，即，使用Blebbistatin时为9 +/-2 Hz，不使用Blebbistatin时为15 +/-4 Hz，并保持了更宽的频谱。在收缩心脏中，在前心室表面VF期间，与使用Blebbistatin的N-PS = 6 +/- 3相比，相位奇点的平均数量为N-PS = 11 +/- 4。Blebbistatin可减少VF诱导。我们发现布比他汀的作用具有浓度依赖性，并且通过洗脱而可逆。除了电生理表征，我们还测量和分析了心脏运动。我们的研究结果可能对光学映射数据的解释产生影响，并强调在离体成像实验中必须仔细考虑生理条件，如氧合和代谢需求。
Optical mapping is a high-resolution fluorescence imaging technique, that uses voltage- or calcium-sensitive dyes to visualize electrical excitation waves on the heart surface. However, optical mapping is very susceptible to the motion of cardiac tissue, which results in so-called motion artifacts in the fluorescence signal. To avoid motion artifacts, contractions of the heart muscle are typically suppressed using pharmacological excitation-contraction uncoupling agents, such as Blebbistatin. The use of pharmacological agents, however, may influence cardiac electrophysiology. Recently, it has been shown that numerical motion tracking can significantly reduce motion-related artifacts in optical mapping, enabling the simultaneous optical measurement of cardiac electrophysiology and mechanics. Here, we combine ratiometric optical mapping with numerical motion tracking to further enhance the robustness and accuracy of these measurements. We evaluate the method's performance by imaging and comparing cardiac restitution and ventricular fibrillation (VF) dynamics in contracting, non-working vs. Blebbistatin-arrested Langendorff-perfused rabbit hearts (N = 10). We found action potential durations (APD) to be, on average, 25 +/- 5% shorter in contracting hearts compared to hearts uncoupled with Blebbistatin. The relative shortening of the APD was found to be larger at higher frequencies. VF was found to be significantly accelerated in contracting hearts, i.e., 9 +/- 2Hz with Blebbistatin and 15 +/- 4Hz without Blebbistatin, and maintained a broader frequency spectrum. In contracting hearts, the average number of phase singularities was N-PS = 11 +/- 4 compared to N-PS = 6 +/- 3 with Blebbistatin during VF on the anterior ventricular surface. VF inducibility was reduced with Blebbistatin. We found the effect of Blebbistatin to be concentration-dependent and reversible by washout. Aside from the electrophysiological characterization, we also measured and analyzed cardiac motion. Our findings may have implications for the interpretation of optical mapping data, and highlight that physiological conditions, such as oxygenation and metabolic demand, must be carefully considered in ex vivo imaging experiments.