The overall objective of this Program Project is to achieve a better understanding of the mechanisms of arrhythmias causing sudden cardiac death. Project 2 tackles the ionic and cellular mechanisms of early (EADs) and delayed (DADs) afterdepolarizations. EADs are classically attributed to reactivation of the L-type Ca current or to spontaneous SR Ca release (i.e. SR Ca release not directly gated by the L-type Ca current) in the setting of reduced repolarization reserve. DADs are attributed to spontaneous SR Ca release in the form of Ca waves stimulating Ca-sensitive inward currents such as Na-Ca exchange. Recently, we have presented evidence for a mechanism (chaos synchronization) by which EADs simultaneously create triggers and enhance tissue substrate vulnerability to promote lethal arrhythmias. A comparable theory does not yet exist for DADs. The goals of this project are: i) to explore the cellular basis of EADs that set the process of chaos synchronization in motion;ii) to test whether theoretically-predicted rotors mediated by the L-type Ca current (related to the biexcitability of cardiac tissue) can be detected experimentally in cardiac tissue as a mechanism of Torsades de pointes;iii) to explore the cellular basis of DADs, specifically how the microscopic behavior of Ca release units in the subcellular Ca cycling network integrates to generate Ca alternans, Ca waves and DADs at the whole cell level;iii) to explore the interactions between EADs and DADs that together generate triggers and modify tissue substrate by increasing tissue electrical dispersion predisposing to VF. To accomplish these goals, we will combine patch clamp (including a new dynamic clamp technique) and fluorescent dye studies at the cellular level with optical mapping studies at the tissue level. These studies will be performed in close collaboration with the mathematical modeling studies in Project 1, the tissue level studies in Project 3, and the therapeutic development in Project 4, and will utlize both Core A and B for support.

Public Health Relevance

The proposed research will study the mechanisms of sudden cardiac death due to ventricular arrhythmias, which takes the lives of more than 300,000 U.S. citizens each year. The goal is to use this information to develop novel therapies to prevent this deadly manifestation of heart disease.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Program Projects (P01)
Project #
2P01HL078931-06A1
Application #
8133290
Study Section
Special Emphasis Panel (ZHL1-PPG-S (F1))
Project Start
2011-04-01
Project End
2016-03-31
Budget Start
2011-06-01
Budget End
2012-05-31
Support Year
6
Fiscal Year
2011
Total Cost
$499,125
Indirect Cost
Name
University of California Los Angeles
Department
Type
DUNS #
092530369
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
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Yin, Dechun; Hsieh, Yu-Cheng; Tsai, Wei-Chung et al. (2017) Role of Apamin-Sensitive Calcium-Activated Small-Conductance Potassium Currents on the Mechanisms of Ventricular Fibrillation in Pacing-Induced Failing Rabbit Hearts. Circ Arrhythm Electrophysiol 10:e004434
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Choi, Eue-Keun; Zhao, Ye; Everett 4th, Thomas H et al. (2017) Ganglionated plexi as neuromodulation targets for atrial fibrillation. J Cardiovasc Electrophysiol 28:1485-1491
Tsai, Wei-Chung; Chan, Yi-Hsin; Chinda, Kroekkiat et al. (2017) Effects of renal sympathetic denervation on the stellate ganglion and brain stem in dogs. Heart Rhythm 14:255-262
Yuan, Yuan; Hassel, Jonathan L; Doytchinova, Anisiia et al. (2017) Left cervical vagal nerve stimulation reduces skin sympathetic nerve activity in patients with drug resistant epilepsy. Heart Rhythm 14:1771-1778
Shen, Mark J; Coffey, Arthur C; Straka, Susan et al. (2017) Simultaneous recordings of intrinsic cardiac nerve activity and skin sympathetic nerve activity from human patients during the postoperative period. Heart Rhythm 14:1587-1593
Weiss, James N; Qu, Zhilin; Shivkumar, Kalyanam (2017) Electrophysiology of Hypokalemia and Hyperkalemia. Circ Arrhythm Electrophysiol 10:
Karagueuzian, Hrayr S; Pezhouman, Arash; Angelini, Marina et al. (2017) Enhanced Late Na and Ca Currents as Effective Antiarrhythmic Drug Targets. Front Pharmacol 8:36

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