The applicant's have shown that structural remodeling of gap junctions, characterized by increased connexin43 along the lateral myocyte membranes, occurs in reentrant circuits that cause ventricular tachycardia in canine infarcted hearts. This discovery has led to this proposal in which the objectives are; 1) to determine the role of gap junction structural remodeling and altered gap junction physiology (electrophysiological remodeling) that occur as a consequence of myocardial infarction, in causing slow an discontinuous conduction necessary for reentrant excitation and 2) to determine how remodeled gap junctions in reentrant circuits affect the response of ventricular arryhthmias to anti-arrhythmic drugs. To accomplish these objectives, a canine infarct model of reentrant circuits in the epicardial border zone will be investigated with different methodologies designed to elucidate structured, electrophysiology and pharmacology of gap junctions. These include in vivo activation mapping, immunolocalization of connexin proteins, and measurements of transjunctional conductances in myocyte cell pairs from the infarct border zone. The different methods will be integrated to investigate the following questions. Does the pattern of structural gap junction remodeling determine the size, shape and location of reentrant circuits and the kinds of arrhythmias which occur? How does gap junctional remodeling of influence propagation of electrical activity i.e. does it cause discontinuous conduction and conduction block? Is structural remodeling associated with reduction in transjunctional conductance that contributes to slow conduction? Are remodeled gap junctions more sensitive to changes in intracellular calcium, possibly explaining the occurrence of conduction block during rapid heart rates or after pharmacologically increasing the L-type calcium current? Does an increased sensitivity of remodeled gap junctions to pH play a role in causing slow activation and conduction in regions with poor gap junction coupling? And, are remodeled gap junctions a sensitive target for drug induced termination of reentrant arrhythmias? When the answers to those questions are obtained, the applicants assert that they will have a comprehensive picture of the electrophysiological and pharmacological consequences of gap junctional remodeling in ischemic heart disease. Gap junctions will be shown to be an important target for drug development to prevent sudden arrhythmic death.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Program Projects (P01)
Project #
2P01HL030557-16
Application #
6336624
Study Section
Project Start
2000-08-01
Project End
2001-07-31
Budget Start
Budget End
Support Year
16
Fiscal Year
2000
Total Cost
$225,543
Indirect Cost
Name
Columbia University (N.Y.)
Department
Type
DUNS #
167204994
City
New York
State
NY
Country
United States
Zip Code
10032
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Ciaccio, Edward J; Ashikaga, Hiroshi; Kaba, Riyaz A et al. (2007) Model of reentrant ventricular tachycardia based on infarct border zone geometry predicts reentrant circuit features as determined by activation mapping. Heart Rhythm 4:1034-45
Ciaccio, Edward J; Micheli-Tzanakou, Evangelia (2007) Development of gradient descent adaptive algorithms to remove common mode artifact for improvement of cardiovascular signal quality. Ann Biomed Eng 35:1146-55
Cabo, Candido; Boyden, Penelope A (2006) Heterogeneous gap junction remodeling stabilizes reentrant circuits in the epicardial border zone of the healing canine infarct: a computational study. Am J Physiol Heart Circ Physiol 291:H2606-16
Cabo, Candido; Yao, Jianan; Boyden, Penelope A et al. (2006) Heterogeneous gap junction remodeling in reentrant circuits in the epicardial border zone of the healing canine infarct. Cardiovasc Res 72:241-9
Terrenoire, Cecile; Clancy, Colleen E; Cormier, Joseph W et al. (2005) Autonomic control of cardiac action potentials: role of potassium channel kinetics in response to sympathetic stimulation. Circ Res 96:e25-34
Fishman, Glenn I (2005) Gap junction remodeling and ventricular arrhythmias. Heart Rhythm 2:887-9
Ciaccio, Edward J; Saltman, Adam E; Hernandez, Oscar M et al. (2005) Multichannel data acquisition system for mapping the electrical activity of the heart. Pacing Clin Electrophysiol 28:826-38
Baba, Shigeo; Dun, Wen; Cabo, Candido et al. (2005) Remodeling in cells from different regions of the reentrant circuit during ventricular tachycardia. Circulation 112:2386-96
Ciaccio, Edward J (2005) Ventricular tachycardia duration and form are associated with electrical discontinuities bounding the core of the reentrant circuit. J Cardiovasc Electrophysiol 16:646-54

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