To create a method capable of yielding images of a cell as its voltage changes, Dr. Salama teamed up with Alan Waggoner, Ph.D., and Lauren Ernst, Ph.D., of Carnegie Mellon's Molecular Biosensor and Imaging Center (MBIC). Together, they developed the long wavelength, voltage-sensitive dyes described in the paper.
The PGH dyes emit fluorescent light according to changes in voltage across cell membranes that are produced by activity of sodium and potassium channels, which open and close as the cell's voltage changes. The dyes make it possible to actually see changes in the electrical potential of a single cell, multiple cells, or even the entire heart. Importantly, the researchers found that the PGH dyes also could be used simultaneously with other probes, such as for calcium, to provide a more complete picture of the processes influencing normal and abnormal rhythms. They can now map, in real time, action potentials, or voltage changes, of cardiac cells below the surface of the heart while following calcium transients (a measure of the local force generated by each cell) during each action potential.
"A unique feature of the PGH dyes is their large Stokes shifts, the wavelength difference between excitation and fluorescence, which make them particularly advantageous for simultaneously mapping action potentials and calcium transients with less interference and therefore greater sensitivity," said Dr. Waggoner, professor of biological sciences and MBIC director, Mellon College of Science, Carnegie Mellon University.
"One of the dyes in
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17-Apr-2006