FIGURE 1.
Respiration in retinas operated closer to maximum capacity, and it was more uncoupled from ATP synthesis than in other tissues. O2 consumption by isolated mouse tissue was measured with a perifusion apparatus (described under “Experimental Procedures”). Vertical dashed lines indicate transitions between media with different components. After O2 consumption stabilized, increasing concentrations of oligomycin were used to inhibit the mitochondrial ATP synthase. FCCP then was added to uncouple respiration from ATP synthesis. Each trace represents an average. Error bars represent S.E. Data are normalized to the initial O2 consumption rate for each experiment. A, O2 consumption by light-adapted mouse retinas (n = 4). The maximum OCR (after adding FCCP) for light-adapted mouse retina averaged from all the analyses done for this report was 0.40 ± 0.13 (S.D.) nmol of O2/min/mg wet weight of retina (n = 11). B, O2 consumption by cerebellum slices (n = 3). Maximum OCR for cerebellum slices was 0.44 ± 0.08 nmol of O2/min/mg (n = 2). C, O2 consumption by pancreatic islets (n = 2, error bars report range). Maximum OCR for islets was 2.1 ± 0.4 nmol of O2/min/mg (n = 2). D, comparison of effects of oligomycin and ouabain on OCR by light-adapted mouse retinas. Neither oligomycin (left, n = 3) nor ouabain (right, n = 4) inhibited retinal O2 consumption by greater than ∼40%. The star indicates that the probability is 0.04 that the inhibition caused by ouabain could be the same or greater than the inhibition caused by oligomycin.