Asymmetry in membrane responses to electric shocks: insights from bidomain simulations. Export

@article{citeulike:611921, abstract = {Models of myocardial membrane dynamics have not been able to reproduce the experimentally observed negative bias in the asymmetry of transmembrane potential changes (DeltaVm) induced by strong electric shocks delivered during the action potential plateau. The goal of this study is to determine what membrane model modifications can bridge this gap between simulation and experiment. We conducted simulations of shocks in bidomain fibers and sheets with membrane dynamics represented by the LRd'2000 model. We found that in the fiber, the negative bias in DeltaVm asymmetry could not be reproduced by addition of electroporation only, but by further addition of hypothetical outward current, Ia, activated upon strong shock-induced depolarization. Furthermore, the experimentally observed rectangularly shaped positive DeltaVm, negative-to-positive DeltaVm ratio (asymmetry ratio) = approximately 2, electroporation occurring at the anode only, and the increase in positive DeltaVm caused by L-type Ca2+-channel blockade were reproduced in the strand only if Ia was assumed to be a part of K+ flow through the L-type Ca2+-channel. In the sheet, Ia not only contributed to the negative bias in DeltaVm asymmetry at sites polarized by physical and virtual electrodes, but also restricted positive DeltaVm. Inclusion of Ia and electroporation is thus the bridge between experiment and simulation.}, address = {Department of Biomedical Engineering, Tulane University, New Orleans, Louisiana 70118, USA. ashta@mbox.kyoto-inet.or.jp}, author = {Ashihara, T. and Trayanova, N. A.}, citeulike-article-id = {611921}, citeulike-linkout-0 = {http://dx.doi.org/10.1529/biophysj.104.043091}, citeulike-linkout-1 = {http://www.biophysj.org/cgi/content/abstract/87/4/2271}, citeulike-linkout-2 = {http://view.ncbi.nlm.nih.gov/pubmed/15454429}, citeulike-linkout-3 = {http://www.hubmed.org/display.cgi?uids=15454429}, doi = {10.1529/biophysj.104.043091}, issn = {0006-3495}, journal = {Biophys J}, keywords = {octwedge, prospectus}, month = {October}, number = {4}, pages = {2271--2282}, posted-at = {2006-07-18 16:01:36}, priority = {3}, title = {Asymmetry in membrane responses to electric shocks: insights from bidomain simulations.}, url = {http://dx.doi.org/10.1529/biophysj.104.043091}, volume = {87}, year = {2004} }

TY - JOUR ID - citeulike:611921 L3 - citeulike-article-id:611921 N2 - Models of myocardial membrane dynamics have not been able to reproduce the experimentally observed negative bias in the asymmetry of transmembrane potential changes (DeltaVm) induced by strong electric shocks delivered during the action potential plateau. The goal of this study is to determine what membrane model modifications can bridge this gap between simulation and experiment. We conducted simulations of shocks in bidomain fibers and sheets with membrane dynamics represented by the LRd'2000 model. We found that in the fiber, the negative bias in DeltaVm asymmetry could not be reproduced by addition of electroporation only, but by further addition of hypothetical outward current, Ia, activated upon strong shock-induced depolarization. Furthermore, the experimentally observed rectangularly shaped positive DeltaVm, negative-to-positive DeltaVm ratio (asymmetry ratio) = approximately 2, electroporation occurring at the anode only, and the increase in positive DeltaVm caused by L-type Ca2+-channel blockade were reproduced in the strand only if Ia was assumed to be a part of K+ flow through the L-type Ca2+-channel. In the sheet, Ia not only contributed to the negative bias in DeltaVm asymmetry at sites polarized by physical and virtual electrodes, but also restricted positive DeltaVm. Inclusion of Ia and electroporation is thus the bridge between experiment and simulation. IS - 4 JF - Biophys J SN - 0006-3495 AD - Department of Biomedical Engineering, Tulane University, New Orleans, Louisiana 70118, USA. ashta@mbox.kyoto-inet.or.jp EP - 2282 TI - Asymmetry in membrane responses to electric shocks: insights from bidomain simulations. VL - 87 SP - 2271 KW - octwedge KW - prospectus AU - Ashihara, T AU - Trayanova, NA PY - 2004/10// UR - http://dx.doi.org/10.1529/biophysj.104.043091 ER -