Institution of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Medical School, University of Verona, Verona, Italy.
J Physiol. 2018 Sep;596(17):3951-3965. doi: 10.1113/JP276239. Epub 2018 Jul 26.
A robust cardiac slicing approach was developed for optical mapping of transmural gradients in transmembrane potential (V ) and intracellular Ca transient (CaT) of murine heart. Significant transmural gradients in V and CaT were observed in the left ventricle. Frequency-dependent action potentials and CaT alternans were observed in all ventricular regions with rapid pacing, with significantly greater incidence in the endocardium than epicardium. The observations demonstrate the feasibility of our new approach to cardiac slicing for systematic analysis of intrinsic transmural and regional gradients in V and CaT.
Transmural and regional gradients in membrane potential and Ca transient in the murine heart are largely unexplored. Here, we developed and validated a robust approach which combines transverse ultra-thin cardiac slices and high resolution optical mapping to enable systematic analysis of transmural and regional gradients in transmembrane potential (V ) and intracellular Ca transient (CaT) across the entire murine ventricles. The voltage dye RH237 or Ca dye Rhod-2 AM were loaded through the coronary circulation using a Langendorff perfusion system. Short-axis slices (300 μm thick) were prepared from the entire ventricles (from the apex to the base) by using a high-precision vibratome. Action potentials (APs) and CaTs were recorded with optical mapping during steady-state baseline and rapid pacing. Significant transmural gradients in V and CaT were observed in the left ventricle, with longer AP duration (APD and APD ) and CaT duration (CaTD and CaTD ) in the endocardium compared with that in the epicardium. No significant regional gradients were observed along the apico-basal axis of the left ventricle. Interventricular gradients were detected with significantly shorter APD , APD and CaTD in the right ventricle compared with left ventricle and ventricular septum. During rapid pacing, AP and CaT alternans were observed in most ventricular regions, with significantly greater incidence in the endocardium in comparison with epicardium. In conclusion, these observations demonstrate the feasibility of our new approach to cardiac slicing for systematic analysis of intrinsic transmural and regional gradients in V and CaT in murine ventricular tissue.
开发了一种稳健的心脏切片方法，用于光学映射小鼠心脏跨壁膜电压（V）和细胞内钙瞬变（CaT）的梯度。在左心室中观察到 V 和 CaT 的明显跨壁梯度。在所有心室区域进行快速起搏时，观察到频率依赖性动作电位和 CaT 交替，在内膜中比心外膜的发生率显著更高。这些观察结果证明了我们新的心脏切片方法用于系统分析 V 和 CaT 的固有跨壁和区域梯度的可行性。
小鼠心脏的膜电位和钙瞬变的跨壁和区域梯度在很大程度上尚未得到探索。在这里，我们开发并验证了一种稳健的方法，该方法结合了横向超薄心脏切片和高分辨率光学映射，可实现对整个小鼠心室的跨壁和区域梯度的系统分析。通过使用 Langendorff 灌注系统将电压染料 RH237 或钙染料 Rhod-2 AM 通过冠状循环加载。通过使用高精度振动切片机从整个心室（从顶点到底部）制备短轴切片（300μm 厚）。在稳态基线和快速起搏期间通过光学映射记录动作电位（APs）和 CaTs。在左心室中观察到 V 和 CaT 的明显跨壁梯度，与心外膜相比，心内膜中的 AP 持续时间（APD 和 APD）和 CaT 持续时间（CaTD 和 CaTD）更长。在左心室的基底轴上未观察到明显的区域梯度。在右心室中检测到室间隔与左心室相比，APD、APD 和 CaTD 明显缩短，存在跨心室梯度。在快速起搏期间，大多数心室区域观察到 AP 和 CaT 交替，与心外膜相比，内膜中的发生率显著更高。总之，这些观察结果证明了我们新的心脏切片方法用于系统分析小鼠心室组织中 V 和 CaT 的固有跨壁和区域梯度的可行性。
