Two dimensional patterns of tissue metabolic states

A photographic method for recording two dimensional patterns of NADH fluorescence of the rat brain in vivo and in freeze trapped samples was developed. Excitation light at 366 nm is provided by a 100 W water cooled Hg arc with Corning 5840 filter. Fluorescence at 450 nm was recorded. Reflectance at 366 nm was measured with the 366 nm pass filter in order to monitor blood volume changes in the brain. The rat brain cortex wubject to anoxia typically showed +30% to +50% changes in fluorescence intensity and -8% to -15% changes in reflectance as determined at specific loci by a microdensitometer (6 rats). Taking advantage of the fact that low temperature significantly increases the quantum yield of NADH fluorescence, fluorescence photographs of brain slices freeze trapped by conventional methods or by ultra rapid cooling were taken. These photographs suggest that metabolic mapping in 2 and ultimately 3 dimensions is possible.