Exploring NADPH oxidases 2 and 4 in cardiac and skeletal muscle adaptations - A cross-tissue comparison

Striated muscle cells, encompassing cardiac myocytes and skeletal muscle fibers, are fundamental to athletic performance, facilitating blood circulation and coordinated movement through contraction. Despite their distinct functional roles, these muscle types exhibit similarities in cytoarchitecture, protein expression, and excitation-contraction coupling. Both muscle types also undergo molecular remodeling in energy metabolism and cell size in response to acute and repeated exercise stimuli to enhance exercise performance. Reactive oxygen species (ROS) produced by NADPH oxidase (NOX) isoforms 2 and 4 have emerged as signaling molecules that regulate exercise adaptations. This review systematically compares NOX2 and NOX4 expression, regulation, and roles in cardiac and skeletal muscle responses across exercise modalities. We highlight the many gaps in our knowledge and opportunities to let future skeletal muscle research into NOX-dependent mechanisms be inspired by cardiac muscle studies and vice versa. Understanding these processes could enhance the development of exercise routines to optimize human performance and health strategies that capitalize on the advantages of physical activity.