Optical Mapping


Voltage‐sensitive fluorescent dyes that bind to cell membranes allow the transmembrane potential to be recorded without insertion of microelectrodes or the use of extracellular electrodes. Such optical mapping is used to record action potentials from cardiac and neuronal tissues.

Keywords: arrhythmia; electrophysiology; heart; ion; voltage; propagation; repolarization

Figure 1.

Schematic diagram of a typical optical mapping system. The preparation is stained with a voltage‐sensitive dye. The optics, which can include single or tandem photographic lenses, microscope objectives, or fibre optics, focus the fluoresced light onto the photodetector. The photodetector can be either a photodiode array or a CCD camera.

Figure 2.

Conceptual representation of electrochromic dye molecules (such as di‐4‐ANEPPS) bound to the cell membrane. The dye responds directly to the membrane's electric field and senses the local values of membrane potential on the time scale of nanoseconds. Absorption of photons by the dye molecule excite it to a higher energy state and causes the emission of a photon of a longer wavelength.

Figure 3.

The mechanism of voltage‐sensitive fluorescence in an electrochromic dye. A change in transmembrane potential causes the fluorescence emission spectrum to shift. The spectral shift alters the magnitude of fluorescent light that is passed by a longpass filter (shaded region). Di‐4‐ANEPPS, for example, exhibits a fluorescence intensity change that varies linearly with membrane potential.

Figure 4.

(a) Optical action potentials from selected sites across the ventricular epicardial surface of a cannulated and perfused guinea‐pig heart. Depolarization times are assigned at the point of most rapid rise of the action potential upstroke. (b) The activation sequence is determined from a relative timing of local depolarizations measured at each of hundreds of recording sites across the surface of the heart.


Further Reading

Dillon SM and Morad MA (1981) A new laser scanning system for measuring action potential propagation in the heart. Science 214: 453–456.

Efimov IR and Mazgalev TN (1998) High‐resolution, three‐dimensional fluorescent imaging reveals multiplayer conduction pattern in the atrioventricular node. Circulation 98: 54–57.

Girouard SD, Laurita KR and Rosenbaum DS (1996) Unique properties of cardiac action potentials recorded with voltage‐sensitive dyes. Journal of Cardiovascular Electrophysiology 7: 1024–1038.

Girouard SD, Pastore JM, Laurita KR, Gregory KW and Rosenbaum DS (1996) Optical mapping in a new guinea pig model of ventricular tachycardia reveals mechanisms for multiple wavelengths in a single reentrant circuit. Circulation 93: 603–613.

Gray RA, Pertsov AM and Jalife J (1998) Spatial and temporal organization during cardiac fibrillation. Nature 392: 75–78.

Knisley SB and Hill BC (1993) Optical recordings of the effect of electrical stimulation on action potential repolarization and the induction of reentry in two‐dimensional perfused rabbit epicardium. Circulation 88: 2402–2414.

Libbus I (1998) Design and Validation of a High Resolution Microscopic Action Potential Mapping System Using Voltage‐sensitive Dyes. MS thesis, Case Western Reserve University, Cleveland, Ohio.

Rohr S, Kucera JP, Fast VG and Kleber AG (1997) Paradoxical improvement of impulse conduction in cardiac tissue by partial cellular uncoupling. Science 275: 841–844.

Rosenbaum DS and Jalife J (eds) (2001) Optical Mapping of Cardiac Excitation and Arrhythmias. Armonk, NY: Futura Pubishing..

Salama G and Morad M (1976) Merocyanine 540 as an optical probe of transmembrane electrical activity in the heart. Science 191: 485–487.

Slavik J (1994) Fluorescent Probes in Cellular and Molecular Biology. Boca Raton, FL: CRC Press.

Witkowski FX, Leon LJ, Penkoske PA et al. (1998) Spatiotemporal evolution of ventricular fibrillation. Nature 392: 78–82.

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How to Cite close
Libbus, Imad, and Rosenbaum, David S(Mar 2002) Optical Mapping. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0003115]