Evans Blue (EBD) is an azo dye which has a very high affinity for serum albumin. It can be useful in physiology in estimating the proportion of body water contained in blood plasma. Evans Blue Dye is widely used to study blood vessel and cellular membrane permeability as it is non-toxic, it can be administered as an intravital dye and it binds to serum albumin – using this as its transporter molecule. The EBD–albumin conjugate (EBA) can be: (i) identified macroscopically by the striking blue colour within tissue; (ii) observed by red auto-fluorescence in tissue sections examined by fluorescence microscopy; and (iii) assessed and quantified by spectrophotometry for serum samples, or homogenised tissue. has recently been utilised in mdx mice to identify permeable skeletal myofibres that have become damaged as a result of muscular dystrophy. EBD has the potential to be a useful vital stain of myofibre permeability in other models of skeletal muscle injury and membrane-associated fragility. Evans Blue is a potent inhibitor of L-glutamate uptake into synaptic vesicles. It also inhibits AMPA and kainate receptor-mediated currents (IC50 values are 220 and 150 nM respectively). P2X-selective purinoceptor antagonist.

Nitroblue Tetrazolium (NBT) is a chromogenic substrate that, like other tetrazolium compounds, can be reduced to produce a colored formazan derivative. Conventionally, a semi-quantitative microscopic NBT assay is used to determine the production of superoxide anion (O2(-)) in various phagocytic cells. This microscopic assay is conducted by counting the cells containing blue NBT formazan deposits, which are formed by reduction of the membrane permeable, water-soluble, yellow-colored, nitroblue tetrazolium (Y-NBT) by O2(-). NBT test, the oldest and most recognized diagnostic test for chronic granulomatous disease (CGD), relies on light microscopy to provide a mostly qualitative determination of phagocyte NADPH oxidase activity: production of blue reduced NBT formazan in normal cells but not in those from patients with CGD. NBT can also be used as a chromogenic activity stain for oxidoreductases in gels or solutions. More commonly NBT is often paired with 5-bromo-4-chloro-3-inolyl phosphate (PCIB) for the colorimetric detection of alkaline phosphatase activity. Alkaline phosphate converts PCIB to a product that reduces NBT to its formazan derivative, resulting in a black-purple precipitate.