L-NIO dihydrochloride is primarily used in research studies to investigate the role of nitric oxide synthase (NOS) in various physiological and pathological processes. It acts as a selective inhibitor of endothelial nitric oxide synthase (eNOS), making it valuable in understanding vascular function and blood pressure regulation. Researchers utilize it to study the impact of reduced nitric oxide production on cardiovascular diseases, such as hypertension and atherosclerosis. Additionally, it is employed in neuroscience to explore the involvement of nitric oxide in neuronal signaling and its potential role in neurodegenerative conditions. Its application extends to experimental models where modulating nitric oxide levels is crucial for examining cellular and molecular mechanisms.