The intersection of exercise, nitric oxide, and metabolism: Unraveling the role of eNOS in skeletal muscle and beyond

Exercise protects against several diseases including cardiometabolic disorders. However, the molecular mechanisms driving these adaptations remain incompletely defined. Endothelial nitric oxide synthase (eNOS), a key source of nitric oxide (NO), is implicated in regulating glucose uptake, fatty acid metabolism, and mitochondrial remodeling in response to exercise. eNOS is expressed in both endothelial and non-endothelial cells and its effects on metabolism are multifaceted. Notably, eNOS is highly expressed in endothelial cells which are ubiquitous throughout all organ systems allowing them to closely integrate with surrounding cell types. This unique feature of the endothelium enables eNOS to influence both local microenvironments and signaling across organ systems. This review summarizes current findings on the role of eNOS-derived NO in exercise metabolism. Evidence suggests eNOS contributes to improved metabolic flexibility, enhanced mitochondrial function, and tissue crosstalk. However, data across experimental models remain mixed, with both supportive and conflicting results. Collectively, the literature indicates that eNOS plays a central, though context-dependent, role in facilitating exercise-induced metabolic benefits. Identifying the specific mechanisms and tissue contributions of eNOS activity remains an important area for future investigation, with potential relevance to metabolic disease prevention and treatment.