Circadian cardiac NAD⁺ metabolism, from transcriptional regulation to healthy aging

Nicotinamide adenine dinucleotide (NAD + ) is a critical redox factor and coenzyme with rhythmic availability, and reduced NAD + levels are a common factor in many disease states, including risk factors associated with aging. Recent studies have expanded on the role of circadian rhythms and the core clock factors that maintain them in the regulation of NAD + levels in the heart. This has revealed that NAD + pools and their use are tightly linked to cardiac function, but also heart failure. The convergence of these fields, namely, clock regulation, heart disease, and NAD + metabolism present a complex network ripe with potential scientific and clinical discoveries, given the growing number of animal models, recently developed technology, and opportunity for safe and accessible precursor supplementation. This review seeks to briefly present known information on circadian rhythms in the heart, connect that research to our understanding of cardiac NAD + metabolism, and finally discuss potential future experiments to better understand interventional opportunities in cardiovascular health regarding these subjects.