ABSTRACT
This chapter suggests that a role for nitric oxide (NO) in modulation of neurotransmitter release, regulation of local cerebral blood flow, circadian rhythms, behavioral state, and arousal. An alternative approach is to study NO physiology on a regional basis. In order to accomplish this goal, the chapter utilises the hemoglobin-trapping technique combined with in vivo microdialysis to measure NO production across behavioral states. The hemoglobin-trapping technique has been used to detect NO production in a variety of applications. The technique is based upon the stoichiometric oxidation of the ferrous form of hemoglobin by NO to produce the ferric form, metHb and nitrate. The oxidation of HbO2 can be quantified using absorbance spectrophotometry, because the color of HbO2 changes from red to brown with oxidation. In order to quantify a change in HbO2 concentration in samples which have been exposed to unknown concentrations of NO, it is necessary to construct a calibration curve to calculate an extinction coefficient.
