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

We have developed a novel autoradiographic method of visualizing oxygen fix ation with sufficient delivery of [O-15]O-2/O-2. Brain slices (400 mu m) we re preincubated in Krebs-Ringer phosphate buffer and exposed to [O-15]O-2 i n a chamber. Fixation of [O-15]O-2 correlated with the polarographically me asured oxygen consumption among tissue slices from various organs (r = 0.84 ). The fixation of [O-15]O-2 by brain slices was significantly reduced (7.2 % of the control) by heat-treatment or dose dependently by NaCN (18.2% of t he control on 50 mM NaCN pretreatment). The O-15 radioactivity in the brain slices prepared from rotenone injected rats was also reduced compared to t he control (56.8% of the control side). In an autoradiographic study,O-15 r adioactivity showed a heterogeneous distribution both in coronal and sagitt al sections. Autoradiography of young and senescent rat brain sections show ed reduction of oxygen uptake with aging in the cerebrum, the senescent bei ng 77.4% of the young. This method provides information regarding basic oxy gen consumption of tissue slices under condition of sufficient O-2 delivery , which reflects mitochondrial electron transport. (C) 1999 Elsevier Scienc e B.V. All rights reserved.