1997 Fiscal Year Final Research Report Summary
Cardiac cell excitation and membrane injury in association with DC defibrillation shocks
| Project/Area Number |
08670779
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Circulatory organs internal medicine
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| Research Institution | (Research Institute of Environmental Medicine) Nagoya University |
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Principal Investigator |
NIWA Ryoko Nagoya Univ., Res.Inst.of Environ.Med., Research Associate, 環境医学研究所, 助手 (00216467)
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| Co-Investigator(Kenkyū-buntansha) |
SAKUMA Ichiro Tokyo Denki Univ., Department of Applied Electronic Engineering., Assistant Prof, 理工学部, 助教授 (50178597)
TOYAMA Junji Nagoya Univ., Res.Inst.of Environ.Med., Professor, 環境医学研究所, 教授 (20023658)
KODAMA Itsuo Nagoya Univ., Res.Inst.of Environ.Med., Professor, 環境医学研究所, 教授 (30124720)
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| Project Period (FY) |
1996 – 1997
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| Keywords | DC shocks / ventricular cells / membrane potential / electroporation / aftereffects / voltage-sensitive dye / tachyarrhythmias / computer simulation |
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| Research Abstract |
The aim of the present study is to elucidate the effects of wide range of electric field (5-100 V/cm) elicited by DC shocks on membrane action potentials of ventricular cells. Experiments through optical signal recording from isolated hearts and computer simulation studies using membrane ionic current models were conducted. 1) Regional differences in arrhythmogenic aftereffects of high intensity DC stimulation in the ventricles, which may reflect reversible breakdown of the cell membrane, were investigated in rabbit hearts stained with a voltage-sensitive dye. Single channel optical action potential signals were recorded from epicardial surface of the right and left ventricular free wall (RVep, LVep) and from the right endocardial surface of the interventricular septum (IVS). High-intensity shocks applied to RVep caused greater aftereffects on membrane potentials (decreases in the resting potential, action potential amplitude and excitability) than those to LVep and IVS.RVep was more susceptible than LVep and IVS for the shock-induced ventricular tachyarrhythmias. 2) A multi-channel optical signal recording system with 8 fiberoptic probes was newly developed. In experiments on rabbit hearts using this system, DC shocks applied to the vulnerable period were shown to cause two different types of ventricular tachycardia (VT) depending on the shock intensity ; polymorphic VT with spiral wave reentry, and monomorphic VT from a focus near the shock application site. 3) In computer simulation studies using Beeler-Reuter model (1977) or Luo-Rudy model (1994), most of the aftereffects of high-intensity shocks were reproduced by setting a large leak membrane conductance or a non-selective ion-permeable pore, which mimics the electroporation.
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