Document Detail

Habitual low-intensity exercise does not protect against myocardial dysfunction after ischemia in rats.
MedLine Citation:
PMID:  15785304     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: It is well established that participation in a chronic exercise program can reduce coronary heart disease (CHD) risk factors and improve myocardial tolerance to ischemia-reperfusion (I-R) injury. Low-intensity exercise programs are known to be effective in reducing CHD risk factors in humans and rats, but whether similar programs are of sufficient intensity to improve intrinsic tolerance to I-R injury has not been established. Thus, the purpose of this study is to determine whether low-intensity exercise provides self-protection to the heart against I-R injury. METHODS: Male, Sprague-Dawley rats were exercised on a treadmill at an intensity of 55-60% VO2max, 40 min/day, 5 days/week for 16 weeks. Reperfusion injury following 20 min of global ischemia was evaluated using the isolated perfused working heart model. Left ventricular content of the cytoprotective protein heat shock protein 70 (HSP70) was determined by Western blotting. RESULTS: The exercise program elevated HSP70 2.7-fold, but did not provide enhanced protection following 20 min of ischemia. Final post-ischemic recovery of cardiac external work was 63+/-9% of pre-ischemic value in the sedentary group (n=9) and 51+/-11% in the exercising group (n=9) (P>0.05). Post-ischemic lactate dehydrogenase release was also similar between groups and the magnitude of release was low, consistent with stunning. CONCLUSIONS: Regular exercise at 55-60% VO2max is below the threshold intensity necessary to induce intrinsic cardioprotection against I-R injury. Furthermore, elevated myocardial HSP70 is not necessarily a marker of improved protection against dysfunction associated with stunning.
Joseph W Starnes; Ryan P Taylor; Joseph T Ciccolo
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  European journal of cardiovascular prevention and rehabilitation : official journal of the European Society of Cardiology, Working Groups on Epidemiology & Prevention and Cardiac Rehabilitation and Exercise Physiology     Volume:  12     ISSN:  1741-8267     ISO Abbreviation:  Eur J Cardiovasc Prev Rehabil     Publication Date:  2005 Apr 
Date Detail:
Created Date:  2005-03-23     Completed Date:  2005-08-04     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  101192000     Medline TA:  Eur J Cardiovasc Prev Rehabil     Country:  England    
Other Details:
Languages:  eng     Pagination:  169-74     Citation Subset:  IM    
Department of Kinesiology and Health Education, Cardiac Metabolism Laboratory, University of Texas, Austin, Texas 78712, USA.
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MeSH Terms
Biological Markers / analysis
Blotting, Western
Disease Models, Animal
Heart Function Tests
Heat-Shock Proteins / analysis*
Ischemic Preconditioning, Myocardial
L-Lactate Dehydrogenase / analysis*
Myocardial Ischemia
Physical Conditioning, Animal*
Random Allocation
Rats, Sprague-Dawley
Reference Values
Reperfusion Injury / physiopathology*,  prevention & control*
Risk Factors
Sensitivity and Specificity
Grant Support
Reg. No./Substance:
0/Biological Markers; 0/Heat-Shock Proteins; EC Dehydrogenase

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