Interaction of nitrite with catalase in the perfused rat liver

The interaction of nitrite with catalase was investigated spectrophotometrically in the perfused rat liver. Real-time spectral changes were obtained using a reflectance scanning spectrophotometer in the liver perfused with a haemoglobin-free medium in a non-recirculating system. Administration of sodium nitrite caused a specific pattern of spectral change indicating the decomposition of catalase compound I to free catalase. The spectral change due to the interaction with nitrite did not occur during potassium cyanide or ethanol infusion, nor in the aminotriazole-pretreated rat liver. The spectral change was observed at concentrations of nitrite in the perfusate over 0.01 mM, and the K0.5 value (the concentration producing half the maximum spectral change) was 0.06 mM. It was concluded that relatively low concentrations of nitrite caused decomposition of catalase compound I in the physiologically functioning liver cell.