NITRIC OXIDE
Nitric oxide (NO) is a ubiquitous gaseous molecule with diverse physiological and pathophysiological roles. It is synthesized from L-arginine by three distinct families of enzymes known as nitric oxide synthases (NOS). NO has been implicated in a wide range of physiological processes such as smooth muscle relaxation, neuronal communication, and immune response (Kumar & Malviya, 2012). NO is also involved in the regulation of blood pressure, platelet aggregation, and vascular integrity (Kumar & Malviya, 2012).
The discovery of NO as a bioactive molecule was a monumental event in the field of biomedicine. NO was first identified by Furchgott and colleagues in the late 1980s (Furchgott et al., 1989). This discovery revolutionized the field of cardiovascular physiology and highlighted the importance of NO in physiological processes. Since then, numerous studies have been conducted to investigate the roles of NO in various physiological and pathophysiological contexts.
NOS is an important enzyme family that is responsible for the synthesis of NO. The enzymes are classified as either constitutive (cNOS) or inducible (iNOS). cNOS is found in the endothelium and is involved in the regulation of vascular tone and other physiological processes. iNOS is found in immune cells and is induced in response to inflammatory stimuli (Kumar & Malviya, 2012). The activity of NOS is tightly regulated by various mechanisms such as calcium-dependent phosphorylation and nitric oxide scavenging (Kumar & Malviya, 2012).
Numerous studies have implicated NO in the pathogenesis of various diseases. For example, NO has been linked to the development of Alzheimer’s disease, stroke, arteriosclerosis, and cancer (Kumar & Malviya, 2012). NO is also involved in the regulation of inflammatory responses, and excessive production of NO has been implicated in inflammation-related disorders such as rheumatoid arthritis (Kumar & Malviya, 2012).
In summary, NO is a ubiquitous gaseous molecule with diverse physiological and pathophysiological roles. NO is synthesized by NOS and is involved in the regulation of vascular tone, blood pressure, platelet aggregation, neuronal communication, and immune response. NO has also been implicated in the pathogenesis of various diseases, including Alzheimer’s disease, stroke, arteriosclerosis, cancer, and rheumatoid arthritis.
References
Furchgott, R.F., Zawadzki, J.V., & Jothianandan, D. (1989). The obligatory role of endothelial cells in the relaxation of arterial smooth muscle by acetylcholine. Nature, 338(6214), 374-376.
Kumar, S., & Malviya, M. (2012). Nitric oxide: A double-edged sword in inflammation. Journal of Cellular and Molecular Medicine, 16(12), 2872-2884.
