Changes in some indices of the synthesis of nitric oxide during the early stages of hepatocarcinogenesis.

Our objective in this study was to determine some indices of the synthesis of nitric oxide during the early periods of diethylnitrosamine-induced hepatocarcinogenesis in mature male rats and to gain insights into their relationship to lipid peroxidation. The basis for the study was the intragastric administration of 10 mg/kg diethylnitrosamine 5 times a week for two months to 28 male rats; 12 additional rats served as untreated controls. During the time-related course of hepatocarcinogenesis, the blood serum level of L-arginine was found to decrease significantly while that of malondialdehyde tended to increase. The superoxide dismutase (SOD) activity increased somewhat during the period of initiation. A significant reduction of SOD was recorded during the period of promotion and a striking increase occurred in the initial period of progression. Unlike SOD, catalase showed a tendency to increase after some initial decline in its activity.