Correlation between light scattering and reduction level of cytochrome oxidase in perfused brains of rats

Abstract

To investigate the correlation between light scattering and tissue viability for brains, we performed multiwavelength diffuse reflectance measurement with perfused brains of rats, in which the reduction level of CuA in cytochrome oxidase was used as an indicator of brain tissue viability. Diffuse reflectance intensity at 620 nm, an isosbestic point of the oxidation-reduction state of cytochrome oxidase, was detected as a scattering signal, while relative diffuse reflectance intensity at 800 nm to that at 620 nm was measured to monitor the absorption change due to the reduction of CuA. After starting perfusion, the scattering signal showed a drastic, triphasic change (increase, decrease and increase) in the time range of 220 – 310 s. After this triphasic change, the scattering signal increased slowly until the end of the measurement (∼ 500 s). The reduction of CuA started and proceeded rapidly during the triphasic scattering change (270 – 310 s). Before and after the triphasic change, we found that light scattering highly correlated with the reduction level of CuA; loss of tissue viability was accompanied by increase in light scattering. These results suggest that the detection of triphasic scattering change is useful to predict loss of tissue viability in brains.