[Interrelation between the phospholipid composition of rat liver plasma membranes and adenylate cyclase activity in the early stages of liver carcinogenesis induced by nitrosodiethylamine].

The content of total phospholipids, the level of cholesterol and individual phospholipids and the activity of basal as well as of NaF-stimulated adenylate cyclase (AC) (EC 4.6.1.1.) in plasma membranes of the rat liver are studied at the initial stages of nitrosodiethylamine-induced hepatocarcinogenesis. Already by the 2nd week a substantial increase in the phospholipid content and a decrease in the cholesterol content are observed. By the 4th week of the experiment the cholesterol content is normalized. In this period the phospholipid content increases sharply and the basal and NaF-stimulated adenylate cyclase activity lowers significantly as compared with the normal level. In the process of hepatocarcinogenesis changes in individual phospholipids and particularly in phosphatidylcholine, lysophosphatidylcholine, and sphingomyelin are observed.