Document Detail

Conscious rabbits become tolerant to multiple episodes of ischemic preconditioning.
MedLine Citation:
PMID:  8156647     Owner:  NLM     Status:  MEDLINE    
Although ischemic preconditioning protects myocardium from infarction in isolated hearts and in anesthetized open-chest animals, its effects have not been examined in unanesthetized animals. Furthermore, it is unknown whether animals become tolerant to multiple episodes of ischemic preconditioning. Rabbits were chronically instrumented with a balloon occluder around a major branch of the left coronary artery for reversible coronary occlusion, a left atrial catheter for radioactive microsphere injections, ECG electrodes for monitoring of myocardial ischemia, and, in some cases, a carotid artery catheter for pressure measurements and timed withdrawal of reference arterial blood samples. Eight control rabbits underwent a 30-minute coronary occlusion and then 180 minutes of reperfusion. Five of the eight rabbits developed ventricular tachycardia or fibrillation during ischemia, and infarct size averaged 37.7 +/- 2.6% of the risk area. Eight rabbits experienced a 5-minute coronary occlusion and 10 minutes of reperfusion before the 30-minute occlusion. In these preconditioned animals, potentially fatal arrhythmias during ischemia were significantly reduced (one of eight, P < .05), and infarct size was much smaller (5.6 +/- 1.1%, P < .0001). The difference could not be explained by hemodynamics or collateral blood flow, which were nearly identical in the two groups. But when the 30-minute coronary occlusion was preceded by 40 to 65 five-minute occlusions during a 3- to 4-day period in seven animals, protection was markedly attenuated. Potentially lethal arrhythmias were very common, and infarct size averaged 26.5 +/- 2.9%, substantially larger than in rabbits with only one preconditioning occlusion (P < .0001).(ABSTRACT TRUNCATED AT 250 WORDS)
M V Cohen; X M Yang; J M Downey
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Circulation research     Volume:  74     ISSN:  0009-7330     ISO Abbreviation:  Circ. Res.     Publication Date:  1994 May 
Date Detail:
Created Date:  1994-05-17     Completed Date:  1994-05-17     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0047103     Medline TA:  Circ Res     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  998-1004     Citation Subset:  IM    
Division of Cardiology, University of South Alabama College of Medicine, Mobile 36688.
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MeSH Terms
Collateral Circulation
Heart Rate / physiology
Myocardial Infarction / pathology*
Myocardial Ischemia / physiopathology*
Time Factors
Ventricular Fibrillation / etiology,  physiopathology
Grant Support

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