FIGURE 1.

Demonstration of steady-state H₂O₂ generation in intact liver by organ spectrophotometry. A, the absorbance difference between 640 and 660 nm is used for monitoring catalase Compound I (top) and oxygen concentration in effluent perfusate (bottom). Anoxia and reoxygenation (argon and oxygen, arrows) and methanol (arrow) as hydrogen donor modulate, and thereby prove the existence of, H₂O₂ steady states; from Sies and Chance (6) with permission. B, catalase minus catalase Compound I difference spectra. Left, isolated enzyme. Right, organ difference spectrum (trace A) and cyanide difference spectrum (trace B); from Sies et al. (8) with permission.