In vivo cooperation between hepatic catalase and superoxide dismutase demonstrated by diethyldithiocarbamate

Abstract

Despite impressive studies of superoxide dismutases (SOD), the actual extent of 02production in living cells remains unknown [ 1,2]. Exceptions are granulocytes and alveolar macrophages which release superoxide anions during phagocytosis [3]. Catalase was first described in 18 12 [4]; nevertheless, it is still debatable whether this enzyme is essential for life in mammalian tissues, In the liver of the anaesthetized rat that hydrogen peroxide is produced and binds to catalase [S]; however, the source of this HzOz is undetermined. We have examined the presence of the catalaseperoxide complex (compound I) in the liver of unanaesthetized guinea pigs, by means of the irreversible inhibition of catalase by 3-amino-1,2,4triazole (AT) administration in vivo. This inhibitor only binds to compound I and not to free catalase [6]. Further to this, the source of hydrogen peroxide was studied by administration of inhibitors of several peroxide producing oxidases. The results indicate that peroxisomal as well as cytoplasmic catalase is active in vivo, and that in unstimulated and physiological conditions superoxide dismutase is providing part of the hydrogen peroxide. Preliminary results have been reported [7].