Figure 4: General mode of operation of the chemiluminescence method for detection of NO. Note: (A) Working model of chemiluniescence method for NO detection. Adapted from Bates, Hetrick and Schoenfisch. (B) Luciferase-based chemiluminescence method for detection of NO concentration in cell cultures. Adapted from Woldman et al. NO: Nitric oxide; PMT: photomultiplier; NO2*: nitrogen dioxide in the excited state; hν: luminescence (h: Planck’s constant, ν: frequency of photon); ONOO–: highly oxidative peroxynitrite; GTP: guanosine triphosphate; cGMP: cyclic guanosine monophosphate; PPi: pyrophosphate; APS: adenosine-5′ phosphosulfate; ATP: adenosine triphosphate; AMP: adenosine monophosphate.