Spatiotemporal neuronal signaling by nitric oxide: diffusion-reaction modeling and analysis.

Nitric oxide (NO) is a neurotransmitter strikingly different from others. It is able to diffuse isotropically regardless of intervening cellular or membrane structures; and it exhibits a surprisingly diverse range of biochemical activity. NO diffusion and reactions affect the nervous system significantly. At present there is no effective technique for detecting them in vivo in real time, whereas computational modeling and simulation helps us gain insight into them. Existing models and simulations for the purpose, however, are inadequate as only the diffusion or only the reactions have been considered. For a comprehensive study of the gaseous neurotransmitter NO, both the diffusion and biochemical reactions should be taken into consideration. This paper, where NO diffusion and reactions are considered as a whole system, presents a spatiotemporal analysis of NO diffusion-reaction, taking the case with brain hypoxia as an example. The analysis is illustrated with a diffusion-reaction model and graphic simulation, which particularly describe how the concentration of oxygen (O2) affects NO signaling in a neuron involved in brain hypoxia.