Optical mapping approaches to cardiac electrophysiological functions.

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.