Mitochondrial ATP Synthase Activity Atlas Reveals the Impact of Sex and Age on Energy Production Across the Lifespan

Mitochondrial dysfunction, a hallmark of aging, profoundly impacts cellular energy production, metabolic regulation, and overall physiological function. ATP synthase (Complex V), a critical enzyme in oxidative phosphorylation, synthesizes adenosine triphosphate (ATP), the primary energy currency of cells. Age-related declines in ATP synthase efficiency contribute to metabolic dysregulation, oxidative stress, and susceptibility to age-related diseases. Despite its importance, no standardized reference delineates normal and pathological variations in ATP synthase activity across tissues, ages, or sexes. This study hypothesizes that ATP synthase activity varies significantly with tissue type, age, and sex, reflecting distinct patterns of metabolic adaptation or dysfunction.Using acidification rate (AR) measurements on a Seahorse XF Analyzer, we quantified ATP synthase activity in 32 tissues from young (10 weeks) and old (80 weeks) male and female mice, with 10 mice per group, generating an atlas from 1,280 samples. This comprehensive dataset provides an unprecedented systems-level view of ATP synthase function across tissues and organ systems with varying bioenergetics. Our findings revealed significant age- and sex-dependent differences in ATP synthase activity. In young males, energy-intensive tissues such as the tongue, diaphragm, and heart atria exhibited high activity, reflecting robust metabolic demands during youth. In young females, elevated activity in the heart atria, cortex, and duodenum highlighted energy demands for neural and digestive processes. Adipose tissues, including inguinal white adipose tissue (iWAT) and gonadal white adipose tissue (gWAT), exhibited higher activity in young females, underscoring sex-specific roles in energy storage and mobilization. Older males demonstrated increased activity in the liver, tongue, and specific skeletal muscle groups, suggesting localized adaptations to sustain energy homeostasis. Older females, in contrast, experienced broader declines in tissues such as the liver, diaphragm, and adipose depots, potentially linked to age-dependent hormonal changes. Neural tissues, including the hippocampus and cerebellum, showed greater stability in females, while skeletal muscle activity remained more robust in aging males, reflecting sex-specific resilience and adaptation.Notably, age emerged as the dominant factor influencing ATP synthase activity, whereas the impact of sex was less pronounced. These results underscore the link between ATP synthase activity and metabolic health, highlighting how tissues adapt—or fail to adapt—to aging and sex-specific physiological demands. By identifying tissue-specific benchmarks for ATP synthase activity, this study establishes a framework for understanding mitochondrial role in aging and sex-based metabolic regulation, offering actionable insights for therapeutic strategies to preserve mitochondrial efficiency, promote healthy aging, and mitigate age-related diseases. The funding source for this study is NIDDK (grant # DK084171). This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.