Journal article
The Maximal Downstroke of Epicardial Potentials as an Index of Electrical Activity in Mouse Hearts
IEEE transactions on biomedical engineering, Vol.58(11), pp.3175-3183
11/2011
DOI: 10.1109/TBME.2011.2164075
PMID: 21859611
Abstract
The maximal upstroke of transmembrane voltage (dV m /dt max ) has been used as an indirect measure of sodium current I Na upon activation in cardiac myocytes. However, sodium influx generates not only the upstroke of V m , but also the downstroke of the extracellular potentials V including epicardial surface potentials V es . The purpose of this study was to evaluate the magnitude of the maximal downstroke of V es (|dV es /dt min |) as a global index of electrical activation, based on the relationship of dV m /dt max to I Na . To fulfill this purpose, we examined |dV es /dt min | experimentally using isolated perfused mouse hearts and computationally using a 3-D cardiac tissue bidomain model. In experimental studies, a custom-made cylindrical "cage" array with 64 electrodes was slipped over mouse hearts to measure V es during hyperkalemia, ischemia, and hypoxia, which are conditions that decrease I Na . Values of |dV es /dt min | from each electrode were normalized (|dV es /dt min | n ) and averaged (|dV es /dt min | na ). Results showed that |dV es /dt min | na decreased during hyperkalemia by 28, 59, and 79% at 8, 10, and 12 mM [K + ] o , respectively. |dV es /dt min | also decreased by 54 and 84% 20 min after the onset of ischemia and hypoxia, respectively. In computational studies, |dV es /dt min | was compared to dV m /dt max at different levels of the maximum sodium conductance G Na , extracellular potassium ion concentration [K + ] o , and intracellular sodium ion concentration [Na + ] i , which all influence levels of I Na . Changes in |dV es /dt min | n were similar to dV m /dt max during alterations of G Na , [K + ] o , and [Na + ] i . Our results demonstrate that |dV es /dt min | na is a robust global index of electrical activation for use in mouse hearts and, similar to dV m /dt max , can be used to probe electrophysiological alterations reliably. The index can be readily measured and evaluated, which makes it attractive for characterization of, for instance, genetically modified mouse hearts and drug effects on cardiac tissue.
Details
- Title: Subtitle
- The Maximal Downstroke of Epicardial Potentials as an Index of Electrical Activity in Mouse Hearts
- Creators
- Kwanghyun Sohn - Nora Eccles Harrison Cardiovascular Research and Training Institute and Bioengineering Department, University of Utah, Salt Lake City, USAFrank B Sachse - Nora Eccles Harrison Cardiovascular Research and Training Institute and Bioengineering Department, University of Utah, Salt Lake City, USAAlonso P Moreno - Nora Eccles Harrison Cardiovascular Research and Training Institute and the School of Medicine, University of Utah, Salt Lake City, USAPhilip R Ershler - Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, USAAdam R Wende - Division of Endocrinology, Metabolism and Diabetes, School of Medicine, University of Utah, Salt Lake City , USAE. Dale Abel - Division of Endocrinology, Metabolism and Diabetes, School of Medicine, University of Utah, Salt Lake City , USABonnie B Punske - Nora Eccles Harrison Cardiovascular Research and Training Institute, the School of Medicine, and Bioengineering Department, University of Utah, Salt Lake City, USA
- Resource Type
- Journal article
- Publication Details
- IEEE transactions on biomedical engineering, Vol.58(11), pp.3175-3183
- Publisher
- IEEE
- DOI
- 10.1109/TBME.2011.2164075
- PMID
- 21859611
- ISSN
- 0018-9294
- eISSN
- 1558-2531
- Language
- English
- Date published
- 11/2011
- Academic Unit
- Roy J. Carver Department of Biomedical Engineering; Fraternal Order of Eagles Diabetes Research Center; Biochemistry and Molecular Biology; Endocrinology and Metabolism; Internal Medicine
- Record Identifier
- 9984025290702771
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