Fig. 3.

H₂O₂ consumption by cardiac mitochondria isolated from catalase knockout mice requires respiratory substrate and is insensitive to sodium azide. The concentration of H₂O₂ was measured at indicated times following the addition of 25 μM H₂O₂ to cardiac mitochondria (0.5 mg/ml) isolated from catalase knockout mice: A: respiring on palmitoyl-carnitine (25 μM) and malate (100 μM) in the absence (black circles) and presence of sodium azide (black squares) or sodium azide and iodoacetamide (gray diamonds). B: with no respiratory substrate in the absence (closed circles) or presence of sodium azide (closed squares) or iodoacetamide (gray triangles). C: disrupted by sonication in the absence (black circles) or presence of sodium azide (black squares). Values are presented as the mean ± SD (n = 3).