In a D-galactose-accelerated aging mouse model, rapamycin administered via dietary supplementation significantly reduced atrial fibrillation susceptibility while reversing both electrical and structural atrial remodeling. Mechanistically, rapamycin inhibited HIF-1α transcriptional activity and nuclear translocation, restored mitochondrial morphology and function, improved insulin resistance, and corrected substrate utilization shifts. Critically, mTOR reactivation failed to reverse HIF-1α inhibition, and molecular docking plus isothermal titration calorimetry data suggest rapamycin may directly disrupt HIF-1α dimerization — pointing to a previously underappreciated mTOR-independent pathway.
Atrial fibrillation affects roughly 60 million people globally and its incidence rises steeply with age, yet the metabolic drivers of age-related atrial remodeling remain poorly targeted clinically. This study reframes rapamycin's cardiac benefit beyond simple mTOR inhibition, positioning HIF-1α-driven metabolic reprogramming — specifically the Warburg-like glycolytic shift seen in aging atria — as a tractable therapeutic node. That mechanistic claim is genuinely novel and, if confirmed in human tissue, could open drug-design opportunities targeting HIF-1α dimerization directly.
Limitations are significant: D-galactose accelerated aging is a chemical surrogate with limited fidelity to true chronological aging, the model is murine rather than human, and AF was induced experimentally rather than observed spontaneously. Rapamycin's immunosuppressive side-effect profile also constrains clinical translation. Overall this is an incremental-to-notable mechanistic advance that meaningfully expands the known pharmacology of rapamycin in cardiac aging.