Cerebral cytochrome-C-oxidase copper band quantification in perfluorocarbon exchange transfused cats

Rapid scanning near infrared spectroscopy (730-960 nm) was utilized to determine cat brain cytochrome-c-oxidase after blood-perfluorocarbon (FC-43) exchange. Spectra were carried out before, during, and after the exchange transfusion on cats with preserved somatosensory evoked potentials and microsphere determined cerebral blood flow (CBF). Carbon dioxide (8%) did not produce an increase in CBF. Difference spectra between the hypercapnic state (8% CO2-92% O2) and post mortem, demonstrated the presence of a broad absorption band centered around 820-845 nm which could be attributed to the oxidized low potential copper ion of cytochrome-c-oxidase. We were unable to further oxidize this band by adding carbon dioxide to the inspired gas mixture. This may be due to the near maximal CBF levels present in this preparation. The spectral data support the hypothesis that near infrared spectroscopy can quantify changes in the redox state of cytochrome-c-oxidase.