Catalase-dependent peroxidative metabolism in the alveolar macrophage during phagocytosis.

EVIDENCE FOR THE PRESENCE OF PEROXIDATIVE METABOLISM IN RABBIT ALVEOLAR MACROPHAGES (AM) HAS BEEN OBTAINED FROM THE FOLLOWING OBSERVATIONS: (a) catalase is present in high concentrations; (b) peroxidase activity could not be detected employing guaiacol as substrate; (c) the irreversible inhibition of AM catalase by aminotriazole served as a detection system for H(2)O(2) and demonstrated increased intracellular H(2)O(2) after phagocytosis; (d) formate oxidation, a marker of catalase-dependent peroxidations, occurs in resting AM and is increased by phagocytosis; (c) measurements of H(2)O(2) accumulation in a dialysate of AM demonstrated twofold increase during phagocytosis; and (f) aminotriazole diminishes O(2) utilization and (14)CO(2) production from labelled glucose and pyruvate. It is concluded that, while catalase-dependent H(2)O(2) metabolism is not essential for particle entry, this pathway represents one of the metabolic pathways stimulated by particle entry in the AM.