Optical Mapping Approaches to Cardiac Electrophysiological Functions.

Abstract

Electrophysiology has been one of the most important strategies in cardiac physiology since the mid19th century [1]. The methodology in this field has been improved with the development of electronics, and quite sophisticated techniques using extracellular electrodes, intracellular microelectrodes, and patch electrodes are now widely used. Recently, optical methods for monitoring membrane potential with fast voltage-sensitive dyes were introduced as a new powerful tool for studying cardiac electrical functions. In this article, optical studies of the electrophysiological function of the vertebrate heart are reviewed. HISTORICAL BACKGROUND OF OPTICAL METHODS FOR MONITORING ELECTRICAL ACTIVITYIn 1968, changes in intrinsic light scattering, in birefringence, and in extrinsic 8-anilino-naphtalene-1-sulfonate (ANS) fluorescence associated with an action potential in the squid giant axon were first reported by Cohen et al. [2] and by Tasaki et al. [3]. At first these experiments were carried out to learn about conformation and/or structural changes that might occur during nerve excitation: it was hoped that the observed optical changes might be related to some molecular mechanism(s) of electrical excitation [4]. In additional experiments, however, Cohen, Salzberg, and co-workers indicated that fluorescent changes depended on changes in transmembrane potential [5], and they soon suggested that optical methods might be used for monitoring membrane potential in cells or cellular processes not accessible to microelectrodes [6,7]. Key words: voltage-sensitive dye, optical recording, electrical activity, heart. Abstract:Recently, optical methods for monitoring membrane potential with fast voltage-sensitive dyes have been introduced as a powerful tool for studying cardiac electrical functions. These methods offer two principal advantages over more conventional electrophysiological techniques. One is that optical recordings may be made from very small cells that are inaccessible to microelectrode impalement, and the other is that multiple sites/regions of a preparation can be monitored simultaneously to provide spatially resolved mapping of electrical activity. The former has made it possible to record spontaneous electrical activities in early embryonic precontractile hearts, and the latter has been applied for mapping of the propagation patterns of electrical activities in the cardiac tissue. In this article, optical studies of the electrophysiological function of the vertebrate heart are reviewed.

Optical Mapping of Tachycardia-Like Excitation Evoked by Pacing in the Isolated Rat Atrium

“…After staining, the preparations were washed with several changes of normal bathing solution containing BDM. Neither phototoxic effects nor pharmacological actions could be observed using this dye, of which the bleaching time was fairly long [1][2][3][4][5].…”

“…Electrical pacing at 1 Hz evoked the events of tachycardia-like excitation (TE).Key words: multiple-site optical recording, tachycardia-like excitation, pacing.Optical methods for monitoring membrane potential activity using fast voltage-sensitive dyes, which have several advantages over more conventional electrophysiological techniques, have provided a powerful tool for the mapping studies of excitation spread under arrhythmic conditions [1,2]. These studies are indispensable for understanding the mechanism(s) of the generation and the maintenance of cardiac arrhythmias, in which reentry and/or abnormal automatism may take part.…”

Optical Mapping Analysis of the Spatiotemporal Pattern of Experimental Tachyarrhythmia in Improved Isolated Rat Atrium Preparation

“…In some examples, two ectopic pacemakers appeared simultaneously. We consider that the experiment using the improved preparation is a superb in vitro model of atrial arrhythmia.Key words: rat atrium, voltage-sensitive dye, multiple-site optical recording, circus movement, ectopic pacemaker.To elucidate the basic mechanism(s) of atrial arrhythmia, we have been carrying out experiments using optical methods for monitoring membrane potential activity using fast voltage-sensitive dyes [1,2]. We optically mapped the spread of excitation in the intact isolated rat right atrial preparation during an abnormal state of atrial rhythm, which we termed "tachycardia-like excitation", evoked by electrical stimulation [3][4][5].…”

A Long-Time, High Spatiotemporal Resolution Optical Recording System for Membrane Potential Activity via Real-Time Writing to the Hard Disk

“…The signal-to-noise ratio was sufficient for analyzing the spreading pattern of excitatory waves in frog atria in a single sweep.Key words: long-duration recording, optical recording, real-time writing technique, photodiode array, voltage-sensitive dye.Optical methods for detecting membrane potential using voltage-sensitive dyes have facilitated simultaneous recording from many sites and enabled spatial analysis (for reviews see [1][2][3]). Recently, this technique has become widespread, with the commercial availability of systems with high spatiotemporal-resolution.…”

“…Optical methods for detecting membrane potential using voltage-sensitive dyes have facilitated simultaneous recording from many sites and enabled spatial analysis (for reviews see [1][2][3]). Recently, this technique has become widespread, with the commercial availability of systems with high spatiotemporal-resolution.…”