Gas-tissue autoradiography using [15O] molecular oxygen for visualization of mitochondrial oxygen fixation in brain...

We have developed a novel in vitro autoradiographic method of visualizing oxygen fixation using [15O]O(2). Brain slices (400 microm) are preincubated in Krebs-Ringer phosphate buffer and exposed to [15O]O(2) with carrier O(2) for 10 min on slide glass or on a Millicell-CM membrane in a chamber. After the 15O(2) exposure, the brain slices are placed in contact with an imaging plate. The autoradiograms are analyzed with MacBas to obtain images of the distribution of radioactivity. The [15O]O(2) fixation was more extensive in the gray matter (striatum, thalamus and cerebral cortex) than in the white matter. The fixation of [15O]O(2) in brain slices decreased dose dependently with NaCN concentration. These results indicate that [15O]O(2) is converted into [15O]H(2)O in the brain tissue according to the activity of mitochondrial electron transfer and remains in the tissue. This method provides information regarding the basic oxygen consumption of brain slices of rat and mouse under conditions of sufficient O(2) delivery, which reflects mitochondrial electron transport.