Diamine oxidase activity in regenerating rat liver and in 4-dimethylaminoazobenzene-induced and Yoshida AH 130 hepatomas.

Diamine oxidase (EC 1.4.3.6) activity, measured as delta 1-[14C]pyrroline formation from [14C]putrescine, was studied in homogenates of regenerating liver and of 4-dimethylaminoazobenzene-induced by Yoshida AH 130 hepatomas of rat. The addition in the incubation medium of acetaldehyde increased delta 1-pyrroline formation in normal and regenerating liver that contained aldehyde dehydrogenase but not in hepatomas where this enzymatic activity was very low or virtually absent. Acetaldehyde did not modify the activity of a preparation of hog kidney diamine oxidase, while chloral hydrate and disulfiram, respectively, enhanced and depressed the activity of this enzyme. These results suggest that aldehyde-metabolizing enzymes present in homogenate may interfere with the amount of delta 1-pyrroline formation and that the use of acetaldehyde may give better information on tissue diamine oxidase activity. Diamine oxidase activity, which was very low in normal liver, increased rapidly in regenerating liver and reached maximum values between 16 and 48 hr after hepatectomy. A large increase in diamine oxidase activity, as compared to the values of normal liver, was also observed in 4-dimethylaminoazobenzene and Yoshida ascites hepatomas.