Chapter 13 – The Physical Properties of Nitric Oxide: Determinants of the Dynamics of NO in Tissue

Publisher Summary Although much is known regarding the biologically important chemical reactivity of nitric oxide (NO) and its derivatives, much less is known regarding its dynamics in vivo. Because NO is highly mobile, its actions will be widespread and this movement will be critically important in determining its extent of action. The spatial movement of NO will be determined by its physical properties, specifically its volatility/solubility and diffusibility. This chapter discusses these properties and applies them to the biological situation where there are specific spatial arrangements of sources, sinks, and targets for NO. The increased solubility of NO in hydrophobic phases predicts that membranes are important sites for NO reactivity. Theoretical and experimental evidence suggests that any given NO molecule that reacts intracellularly enters from outside the cell, even if the cell itself synthesizes NO. The overall usefulness of the concept of a “storage form” of NO to prevent its rapid disappearance is discussed and shown to be effective only under certain restrictive conditions.