Visualization of mitochondrial oxygen fixation in brain slices by gas-tissue autoradiography

We have developed a novel autoradiographic method of visualizing oxygen fixation with sufficient delivery of [(15)O]O(2)/O(2). Brain slices (400 microm) were preincubated in Krebs-Ringer phosphate buffer and exposed to [(15)O]O(2) in a chamber. Fixation of [(15)O]O(2) correlated with the polarographically measured oxygen consumption among tissue slices from various organs (r=0.84). The fixation of [(15)O]O(2) by brain slices was significantly reduced (7. 2% of the control) by heat-treatment or dose dependently by NaCN (18. 2% of the control on 50 mM NaCN pretreatment). The (15)O radioactivity in the brain slices prepared from rotenone injected rats was also reduced compared to the control (56.8% of the control side). In an autoradiographic study, (15)O radioactivity showed a heterogeneous distribution both in coronal and sagittal sections. Autoradiography of young and senescent rat brain sections showed reduction of oxygen uptake with aging in the cerebrum, the senescent being 77.4% of the young. This method provides information regarding basic oxygen consumption of tissue slices under condition of sufficient O(2) delivery, which reflects mitochondrial electron transport.