Pittsburgh Being able to witness the precise events that form the heart's orchestral rhythm or the rat-a-tat-tat of irregular heartbeats could enable researchers to better understand the underlying causes of arrhythmias and sudden cardiac death. Indeed, a team from the University of Pittsburgh School of Medicine and Carnegie Mellon University report they have developed unique chemical dyes that have made it possible to see what the naked eye has never seen before: action potentials, or voltage changes, of cardiac cells including those deep inside the heart, which trigger and determine the pace of heartbeats.

The researchers describe seven of these "Pittsburgh" dyes PGH I to IV and VI to VIII, for short in the current issue of the Journal of Membrane Biology. Importantly, the PGH dyes are able to follow the electrical activity of cells several layers below the surface of the heart where the cardiac contractions are initiated and propagated.

"What exactly causes arrhythmias and sudden cardiac death remains an important question we hope to answer through our studies that make use of a combination of novel imaging approaches. Toward this end, these dyes have proved to be particularly important for recording membrane potential changes and capturing in detail, and in real time, the synchronicity or asynchronicity of the heart. Obtaining such images had long been a challenge due to confounding motions of the heart," said lead author Guy Salama, Ph.D., professor of cell biology and physiology at the University of Pittsburgh School of Medicine.

Like a light switch that's quickly flipped on and off, a heart beat begins in similar fashion. A rapid change in electrical charge from negative to positive and back again occurs within each cell, producing a current that takes about 3/10 of a second to spread in a staccato yet fluid motion across the heart. As these voltage changes occur, so do the traffic patterns of potassium, sodium and calcium, each
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17-Apr-2006

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