Spectroscopic Monitoring of NADH: Historical Overview

In the early days, NADH was measured using the absorption properties of the molecule. The discovery of the fluorescence emitted from the reduced form of NAD+ opened up new options to study mitochondria function under in vitro and in vivo conditions. The effects of various perturbations on the redox state of NADH were tested using different preparations at all organization levels, including NADH in solution, isolated mitochondria, cells, tissue slices, and up to in vivo monitoring of various organs of animals. Very small differences in NADH spectra were found between the various levels of biological organization. Significant correlation between NADH fluorescence measured in vivo and in biochemical assay was found. All those issues are described in this chapter.