Spectrofluorimeter for estimating the metabolic state of organs and tissues

A spectrofluorimeter has been developed that measures the intrinsic fluorescence intensity in the emission regions of respiratory coenzymes nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) at wavelengths 465 and 515 nm with excitation at 365 nm and 440 nm. The redox ratio NADH/FAD is used as the main index of the metabolic state of a bio-object. This parameter, because of the different directionality of the NADH and FAD reactions in response to oxidation, possesses higher sensitivity to the change of state of biotissue and depends less on absorption and scattering variations. The diffuse reflectance at 440 nm serves as a supplementary parameter. All the parameters are normalized to normoxia conditions. The NADH-excitation effect is detected at wavelength 440 nm. Using a study of rat heart under ex vivo and in vivo conditions as an example, it is demonstrated that early damage of the myocardium accompanying regional ischemia can be detected.