Increased cyclic AMP levels in malignant hepatic nodules of ethionine treated rats

Cyclic AMP levels were measured in vivo and in vitro in uninvolved liver, benign and malignant hepatic nodules of ethionine treated rats. The in vivo cyclic AMP concentration of 5.0 ± 0.5 nmoles/gm protein in malignant nodules was twice that in benign nodules and uninvolved liver. Values in tissue slices after sacrifice of anesthetized animals were identical to the in vivo levels. Cyclic AMP levels were higher in animals sacrificed by decapitation, but were not influenced by 20 minutes incubation. Concentrations in malignant nodules still exceeded those in the other two tissues. The increased cyclic AMP concentrations in malignant nodules persisted whether the data was expressed on the basis of wet weight, protein or DNA.