February 1, 1997AJP Heart and Circulatory Physiology
Maximum oxidative phosphorylation capacity of the mammalian heart
Key result
The maximum in vivo aerobic ATP production rate of the intact mammalian heart was calculated to be 29.5 and 24.3 micromol O2/min/g wet wt in dogs and pigs, respectively, indicating little aerobic reserve.
Population
Dog and pig myocardium/mitochondria
Design
Preclinical
Authors
Discussion
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Member takes
Implication
Exercising mammalian hearts operate near maximal aerobic capacity; leaves open translation to human cardiac energetics or disease.
Key Points
- To quantify the maximum aerobic ATP production capacity of the mammalian heart independent of blood flow and oxygen delivery limitations.
- Measured maximum ADP-Pi-driven mitochondrial respiratory rate (MVO2 mito) at 37°C with saturating substrates, oxygen, and cofactors in isolated dog and pig heart mitochondria.
- Normalized respiratory rates to cytochrome oxidase (Cyt a) content and quantified tissue-level Cyt a concentration per gram of wet myocardial weight.
- Maximum ADP-Pi-driven respiratory rates were 676 ± 31 nmol O2 · min⁻¹ · nmol Cyt a⁻¹ in dogs and 665 ± 65 nmol O2 · min⁻¹ · nmol Cyt a⁻¹ in pigs.
- Myocardial Cyt a concentrations were 43.6 ± 2.4 nmol/g wet weight (dog) and 36.6 ± 3.1 nmol/g wet weight (pig), yielding calculated maximum tissue MVO2 mito of 29.5 and 24.3 µmol O2 · min⁻¹ · g wet weight⁻¹, respectively.
- Comparison with intact heart workload data showed that an exercising heart utilizes 80% to 90% of its total oxidative capacity.
Structured PICO
P
Population
Dog and pig myocardium/mitochondria
I
Intervention
Measurement of maximum ADP-P(i)-driven heart mitochondrial respiratory rate with saturating levels of oxygen, substrates, and cofactors at 37 degrees C
O
Outcome
Maximum ADP-P(i)-driven heart mitochondrial respiratory rate (MV(O2 mito)) and cytochrome alpha1 alpha3 (Cyt a) contentsurrogate
The exercising mammalian heart utilizes 80-90% of its maximum oxidative capacity, implying there is little aerobic ATP production reserve.
Cite This Study
Mootha et al. (1997) studied Myocardial oxidative phosphorylation capacity. Maximum ADP-P(i)-driven mitochondrial respiratory rate determination was evaluated on Maximum ADP-P(i)-driven heart mitochondrial respiratory rate (MVO2 mito) normalized to cytochrome a content. The maximum in vivo aerobic ATP production rate of the intact mammalian heart was calculated to be 29.5 and 24.3 micromol O2/min/g wet wt in dogs and pigs, respectively, indicating little aerobic reserve.