Dr. Tung studies the functional properties of engineered networks of living cardiac cells at varying structural levels that include single cells, cell strands, 2-D sheets and 3-D tissue. His lab cultures neonatal rat ventricular cells and uses microfabrication techniques to direct the growth of the cells into individual cell shapes or into geometrically patterned multicellular networks.
To visualize the spatial propagation of excitatory wave fronts in the cells over relatively large distances, the Tung lab has developed a method called "contact fluorescence imaging" that can optically map the electrical activity of cell monolayers stained with a voltage-sensitive dye.
With these tools, Dr. Tung and his associates have developed a simple, controlled and cultured cell model suitable for the study of a major form of aberrant propagation called reentry. Reentry underlies many cardiac arrhythmias, including life-threatening ventricular fibrillation and milder forms of tachycardia or flutter in the atria, ventricles, and atrioventricular node. They use theoretical and computational models to complement experimental work and to assist in the interpretation of the maps of electrical activity.
The Tung lab is also investigating the electrophysiological responses of the cell networks to electrical stimulation in the context of electrical cardioversion and defibrillation. Other interests in the lab include the synthesis and characterization of 3-D constructs of cardiac tissue and the use of genetic approaches to alter the electrophysiological characteristics of cardiac cells.
Lab Website: Cardiac Bioelectric Systems Laboratory
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Entcheva, E., Lu, S. N., Harrison, R. L., Sharma, V. and Tung, L. "Contact fluorescence imaging (CFI) of reentry in monolayers of cultured neonatal rat ventricular cells." J Cardiovasc Electrophysiol. 11:665–676, 2000.
Tung, L. and Kleber, A. G. "Virtual sources associated with linear and curved strands of cardiac cells." Am J Physiol Heart Circ Physiol. 279:H1579–H1590, 2000.
Sharma, V. and Tung, L. "A theoretical and experimental study of sawtooth effect in isolated cardiac cell-pairs." J Cardiovasc Electrophysiol. 12:1164–73, 2001.
Sharma, V. and Tung, L. "Effects of uniform electric fields on intracellular calcium transients in single cardiac cells." Am J Physiol Heart Circ Physiol. 282(1):H72–H79, 2002.