ABSTRACT
The development of optical recordings of membrane potential was driven by the need to overcome many obstacles in electrophysiology and the promise of a technology “for measuring membrane potential in systems where, for reasons of scale, topology, or complexity, the use of electrodes is inconvenient or impossible. Investigators discovered molecular probes that bind to the plasma membrane of neuronal and cardiac cells and exhibit changes in fluorescence and/or absorption that mimic changes in transmembrane potential. A significant limitation of optical mapping of the heart is motion artifact introduced by muscle contractions. These “movement” artifacts distort optical action potentials by altering the fluorescence intensity. Any optical imaging system must consist of a two-dimensional optical sensor and a stable light source, such as a laser or dendritic cells-powered tungsten-halogen lamp, mercury source, or light emitting diodes. Optical mapping has made a significant contribution to functional studies of impulse propagation in the conduction system of the heart.
