Figure 2. Superoxide-induced, GDP-sensitive proton conductance of skeletal muscle mitochondria from experimentally immersed penguins.

For details see Methods. A, increased proton conductance in the presence of superoxide. B, inhibition of superoxide-induced proton conductance by addition of GDP. C, inhibition of superoxide-induced proton conductance by addition of superoxide dismutase. ♦, control; □, plus 50 μm xanthine and 0.01 U xanthine oxidase per 2.5 ml; ▴, plus xanthine, xanthine oxidase and 1 mm GDP; •, plus xanthine, xanthine oxidase and 12 U ml⁻¹ superoxide dismutase. All data are means ± s.e.m. of six independent experiments each performed in duplicate.