Document Detail

Attenuation of increased regional myocardial oxygen consumption during exercise as a major cause of warm-up phenomenon.
MedLine Citation:
PMID:  8496525     Owner:  NLM     Status:  MEDLINE    
OBJECTIVES: The aim of this study was to test the hypothesis that the warm-up phenomenon is attributable to a reduction of increased myocardial oxygen consumption rather than to increased coronary blood flow during exercise. BACKGROUND: The underlying mechanism of the warm-up phenomenon is not elucidated. METHODS: Thirteen patients with effort angina were subjected to two consecutive supine ergometer exercise tests performed 15 min apart. All patients had severe proximal stenosis (> 90%) in the left anterior descending coronary artery. Great cardiac vein flow was measured before and during exercise. Both regional myocardial oxygen consumption and adenosine release were determined. RESULTS: Exercise was continued for significantly longer before angina onset in the second than in the first exercise test (507 +/- 44 vs. 410 +/- 42 s, p < 0.01). The extent of ST segment depression in lead V5 of the electrocardiogram (ECG) was larger at the time of angina onset in the first (1.7 +/- 0.2 mm) than in the second (1.1 +/- 0.2 mm, p < 0.01) exercise test. Neither systemic hemodynamic variables nor great cardiac vein flow differed between the first and second exercise tests. In contrast, regional myocardial oxygen consumption assessed at 3 min of exercise was significantly (p < 0.01) less in the second than in the first test (8.0 +/- 0.8 vs. 8.7 +/- 0.9 ml/min). Adenosine release during the second test was higher (p < 0.05) than in the first test (2.5 +/- 0.5 vs. 3.9 +/- 0.5 nmol/min at 3 min of the first and second tests, p < 0.01). CONCLUSIONS: These results indicate that the warm-up phenomenon is not attributable to increased coronary flow but to attenuation of increased regional myocardial oxygen consumption, which may be mediated by adenosine A1 receptor activation.
Y Okazaki; K Kodama; H Sato; M Kitakaze; A Hirayama; M Mishima; M Hori; M Inoue
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of the American College of Cardiology     Volume:  21     ISSN:  0735-1097     ISO Abbreviation:  J. Am. Coll. Cardiol.     Publication Date:  1993 Jun 
Date Detail:
Created Date:  1993-06-22     Completed Date:  1993-06-22     Revised Date:  2010-03-24    
Medline Journal Info:
Nlm Unique ID:  8301365     Medline TA:  J Am Coll Cardiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1597-604     Citation Subset:  AIM; IM; S    
Osaka University School of Medicine, Japan.
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MeSH Terms
Adaptation, Physiological
Adenosine / blood
Angina Pectoris / blood,  metabolism*,  physiopathology*
Coronary Circulation*
Middle Aged
Myocardium / metabolism*
Norepinephrine / blood
Oxygen Consumption*
Physical Exertion*
Reg. No./Substance:
51-41-2/Norepinephrine; 58-61-7/Adenosine

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