Age-related changes of myocardial ATP supply and demand mechanisms

• Age-related changes in cardiac energetics are discussed.
• It is controversial if ATP production, delivery, or utilization change during aging.
• Results from isolated mitochondria frequently differ from those obtained in tissue.
• Unresolved and controversial questions requiring further studies are highlighted.

In advanced age, the resting myocardial oxygen consumption rate (MVO2) and cardiac work (CW) in the rat remain intact. However, MVO2, CW and cardiac efficiency achieved at high demand are decreased with age, compared to maximal values in the young. Whether this deterioration is due to decrease in myocardial ATP demand, ATP supply, or the control mechanisms that match them remains controversial. Here we discuss evolving perspectives of age-related changes of myocardial ATP supply and demand mechanisms, and critique experimental models used to investigate aging. Specifically, we evaluate experimental data collected at the level of isolated mitochondria, tissue, or organism, and discuss how mitochondrial energetic mechanisms change in advanced age, both at basal and high energy-demand levels.