Non-invasive near infrared spectroscopy of brain in fluorocarbon exchange-transfused rats

Near infrared spectra (700-930 nm) were recorded from the head of anesthetized rats before and after blood substitution with a fluorocarbon emulsion. A large band, centered at 850 nm and characteristic of oxidized cytochrome a, a3, was evidenced in hemoglobin-free living animals. Variations in the amplitude of this absorption band were observed under different respiratory conditions.