Figure 5: Different ways adopted for monitoring NO levels using chemiluminescence method. Note: (A) Experimental setup for in vivo NO monitoring. Adapted from Yao et al. (B) Schematic representation of hollow fiber gas-liquid exchange module. Chemiluminescence reaction occurs when the gas, which flows along the exterior diffuses through the pores in the fiber membrane and into the luminol/H2O2 solution flowing through the interiors of the fiber. Adapted from Robinson et al. (C) Membrane phase and reaction chemistry for the nitric oxide fiber-optics sensor. Adapted from Zhou and Arnold. C: Snail shell-like cell; M: mixer; P: microdialysis probe; PM: photomultiplier tube; NO: nitric oxide; S1–3: syringes for different streams; PMT: photomultiplier; ONOO–: highly oxidative peroxynitrite; hν: luminescence (h: Planck’s constant, ν: frequency of the photon).