Girouard S D, Laurita K R, Rosenbaum D S
Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA.
J Cardiovasc Electrophysiol. 1996 Nov;7(11):1024-38. doi: 10.1111/j.1540-8167.1996.tb00478.x.
Optical mapping with voltage-sensitive dyes has made it possible to record cardiac action potentials with high spatial resolution that is unattainable by conventional techniques. Optically recorded signals possess distinct properties that differ importantly from electrograms recorded with extracellular electrodes or action potentials recorded with microelectrode techniques. Despite the growing application of optical mapping to cardiac electrophysiology, relatively little quantitative information is available regarding the characteristics of optical action potentials recorded from cardiac tissue.
A high-resolution optical mapping system and microelectrode techniques were used to determine the characteristics of guinea pig ventricular action potentials recorded with the voltage-sensitive dye di-4-ANEPPS. The effects of optical magnification, tissue-light interaction, sampling rate, voltage resolution, spatial resolution, and cardiac motion on action potential signal characteristics were determined. The optical action potential signal represents the relative change in transmembrane potential arising from a volume of cells, where the area of a recording site is determined by optical magnification and detector area, and the depth of recording is determined by system optics and the visible light transmission characteristics of cardiac muscle. Using photographic lenses, the depth of tissue contributing to the signal is < 250 microns. The action potential plateau and final repolarization can be accurately reconstructed from data digitized at modest sampling rates (450 to 750 Hz), since the frequency content of optical action potentials is band-limited to approximately 150 Hz. However, faster sampling rates are needed to depict the subtle details of the action potential upstroke. In addition to temporal resolution, it is essential to achieve sufficient dynamic range and voltage resolution to accurately represent the time course of membrane potential change. Voltage resolution is inversely related to the square of spatial resolution, hence, there exists an inherent trade-off between increased spatial resolution and diminished voltage resolution. Cardiac motion, which can otherwise limit spatial resolution as well as signal fidelity, can be effectively reduced using mechanical stabilization of the heart without distorting action potential characteristics.
Optical mapping with voltage-sensitive dyes provides high-fidelity multisite action potential recording with flexible spatial resolution. When recording cardiac action potentials with voltage-sensitive dyes, the interdependence of temporal, spatial, and voltage resolutions must be carefully considered.
使用电压敏感染料进行光学标测能够以高空间分辨率记录心脏动作电位，这是传统技术无法实现的。光学记录的信号具有与细胞外电极记录的心电图或微电极技术记录的动作电位显著不同的特性。尽管光学标测在心脏电生理学中的应用越来越广泛，但关于从心脏组织记录的光学动作电位的特征，相对较少有定量信息。
使用高分辨率光学标测系统和微电极技术来确定用电压敏感染料di-4-ANEPPS记录的豚鼠心室动作电位的特征。确定了光学放大倍数、组织与光的相互作用、采样率、电压分辨率、空间分辨率和心脏运动对动作电位信号特征的影响。光学动作电位信号代表由一定体积的细胞产生的跨膜电位的相对变化，其中记录位点的面积由光学放大倍数和探测器面积决定，记录深度由系统光学和心肌的可见光透射特性决定。使用摄影镜头时，对信号有贡献的组织深度小于250微米。由于光学动作电位的频率成分被限制在约150Hz，因此可以从以适度采样率（450至750Hz）数字化的数据中准确重建动作电位平台期和最终复极化。然而，需要更快的采样率来描绘动作电位上升支的细微细节。除了时间分辨率外，实现足够的动态范围和电压分辨率以准确表示膜电位变化的时间过程也至关重要。电压分辨率与空间分辨率的平方成反比，因此，在提高空间分辨率和降低电压分辨率之间存在固有的权衡。心脏运动否则会限制空间分辨率以及信号保真度，使用心脏的机械稳定可以有效减少心脏运动，而不会扭曲动作电位特征。
使用电压敏感染料进行光学标测可提供具有灵活空间分辨率的高保真多部位动作电位记录。在用电压敏感染料记录心脏动作电位时，必须仔细考虑时间、空间和电压分辨率的相互依赖性。
