Document Detail

Effect of oxygen withdrawal on active and passive electrical properties of arterially perfused rabbit ventricular muscle.
MedLine Citation:
PMID:  2917379     Owner:  NLM     Status:  MEDLINE    
Oxygen withdrawal from myocardial cells leads to changes of the transmembrane action potential (mainly action potential shortening), to cellular uncoupling, and to changes of vascular permeability. This study was aimed at the simultaneous measurement of electrical activity and passive electrical properties (extracellular and intracellular longitudinal resistance) in arterially perfused rabbit papillary muscles under different conditions of changed oxygen supply. These included 1) complete anoxia (erythrocyte-free perfusate), 2) hypoxia (PO2 between 23-28 mm Hg, erythrocytes present) in the presence and absence of glucose, and 3) normoxia with erythrocyte-free perfusate. Similarly to myocardial ischemia, rapid cellular uncoupling occurred only after an initial stable period of approximately 17 minutes, and it required complete anoxia. The marked shortening of the action potential developed before cellular uncoupling. In six out of eight experiments, the fibers were inexcitable when uncoupling started. In severe hypoxia, no significant change of internal longitudinal resistance was observed over 35-40 minutes. The time course of the extracellular longitudinal resistance was different from the change in intracellular resistance: A marked decrease occurred almost immediately after the onset of oxygen withdrawal. This decrease was followed by a small increase in conduction velocity, which was most likely due to a change in the interstitial compartment (edema). It was observed during anoxic as well as during hypoxic perfusion. We conclude that 1) cellular uncoupling in arterially perfused tissue requires almost complete oxygen lack and occurs with a delay of more than 10 minutes, 2) marked action potential shortening precedes uncoupling, and therefore can not simply be attributed to an increase in free, intracellular calcium, and 3) vascular endothelial function is more sensitive to oxygen withdrawal than the myocyte.
C B Riegger; G Alperovich; A G Kléber
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Circulation research     Volume:  64     ISSN:  0009-7330     ISO Abbreviation:  Circ. Res.     Publication Date:  1989 Mar 
Date Detail:
Created Date:  1989-04-05     Completed Date:  1989-04-05     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0047103     Medline TA:  Circ Res     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  532-41     Citation Subset:  IM    
Department of Physiology, University of Berne, Switzerland.
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MeSH Terms
Action Potentials
Anoxia / physiopathology
Electric Conductivity
Membrane Potentials
Oxygen / administration & dosage*
Papillary Muscles / physiology*
Perfusion / methods
Time Factors
Ventricular Function
Reg. No./Substance:

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