Asthma Nitric Oxide
Arginine is the source of nitric oxide using the enzyme NOS. Inducible NOS is expressed in response to triggers of inflammation mediated by NFkB. NO in turn activates guanylate cyclase to increase cyclic GMP and cGMP relaxes muscle actin and myosin. Studies are being made to assess the status of asthma by measuring nitric oxide (NO) in respired air. Since NO is produced as a product of the action of induced nitric oxide synthase (iNOS), and iNOS is synthesized when the inflammatory transcription factor NFkB is activated, then the inflammation that is a characteristic of asthma should be signaled by the production of NO. If NO is involved in asthma, then one would expect relaxation of muscle to occur. That is the opposite of what is observed; contraction of the muscle cells surrounding airways is responsible for airway constriction is asthmatic episodes. Thus, during asthmatic episodes NO must be reduced. Since NO is made from the amino acid arginine, then the ability to p...