Abstract
Image-guided, spatially localized 31P magnetic resonance spectroscopy (MRS) was used to study in vivo murine cardiac metabolism under resting and dobutamine-induced stress conditions. Intravenous dobutamine infusion (24 μg · min-1 · kg body wt-1) increased the mean heart rate by ∼39% from 482 ± 46 per min at baseline to 669 ± 77 per min in adult mice. The myocardial phosphocreatine (PCr)-to-ATP (PCr/ATP) ratio remained unchanged at 2.1 ± 0.5 during dobutamine stress, compared with baseline conditions. Therefore, we conclude that a significant increase in heart rate does not result in a decline in the in vivo murine cardiac PCr/ATP ratio. These observations in very small mammals, viz., mice, at extremely high heart rates are consistent with studies in large animals demonstrating that global levels of high-energy phosphate metabolites do not regulate in vivo myocardial metabolism during physiologically relevant increases in cardiac work.
Original language | English (US) |
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Pages (from-to) | H1976-H1979 |
Journal | American Journal of Physiology - Heart and Circulatory Physiology |
Volume | 285 |
Issue number | 5 54-5 |
DOIs | |
State | Published - Nov 2003 |
Keywords
- Cardiac metabolism
- Dobutamine stress
- Magnetic resonance spectroscopy
- PCr-to-ATP ratio
ASJC Scopus subject areas
- Physiology
- Cardiology and Cardiovascular Medicine
- Physiology (medical)