Electrical uncoupling and increase of extracellular resistance after induction of ischemia in isolated, arterially perfused rabbit papillary muscle.

Author:

Kléber A G,Riegger C B,Janse M J

Abstract

Extracellular and intracellular longitudinal resistances (ro and ri), transmembrane potentials, and conduction velocity were determined in arterially blood-perfused rabbit papillary muscles. Cable analysis was made possible by placing the muscle in a H2O-saturated gaseous environment, which acted as an electrical insulator. Ischemia was produced by exchanging the O2 in the atmosphere by N2 (94% N2-6% CO2) in addition to arresting coronary flow. The first 10-15 minutes of ischemia were characterized by an increase in ro, while ri remained constant. The early part of the increase in ro coincided with the drop in perfusion pressure and was probably due to the diminution of intravascular volume. Rapid electrical uncoupling, reflected by an increase in ri (threefold within 5 minutes), occurred thereafter. The dissociation between the early increase in ro and the delayed increase in ri produced an initial increase in the ratio ro:ri, which subsequently decreased. The decrease in conduction velocity was less than observed in intact hearts with ischemia. This difference is explained by the relatively small changes in resting membrane potential and action potential amplitude in the preparation used. Our results suggest that in the early, reversible phase of ischemia, the increase in ro contributes to a small but significant extent to the slowing of conduction. After 15-20 minutes, the rapid cellular uncoupling, which was most likely coincident with breakdown of cellular homeostasis, may contribute to the occurrence of arrhythmias during this phase of ischemia. Moreover, the early change in the ratio ro:ri will influence the amplitude of the extracellular electrograms following coronary occlusion (TQ-segment and ST-segment shifts).

Publisher

Ovid Technologies (Wolters Kluwer Health)

Subject

Cardiology and Cardiovascular Medicine,Physiology

Reference36 articles.

1. The diffusion of radiopotassium across intercalated disks of mammalian cardiac muscle;Weidmann S;J Phvsiol,1966

2. Weidmann S: Electrical constants of trabecular muscle from mammalian heart. J Physiol i970;210:1041 -1054

3. Cranefield PF: The Conductionof the CardiacImpulse. Mount Kisco New York Future Publishing Company 1975

4. Ueber die Leitung der Erregung im Herzmuskel;Engelmann TW;PflugersArch,1875

5. The recovery of resting potential and input resistance in sheep heart injured by knife or laser

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3