Effect of thyroxine, insulin and cholesterol on the amount of cyclic adenosine monophosphate in normal and oncornavirus infected cells]

The intracellular concentration of cyclic AMP in normal cells and in cells infected with the Rous sarcoma virus (chicken fibroblasts) was determined by the method of saturation analysis (method of concurrent binding with protein). Thyroxine (2 mcg/ml) increased the level of cyclic AMP both in normal and infected cells, insulin (2 mcg/ml) decreased the concentration of cyclic AMP in infected cells, but cholesterol (5 mcg/ml) exerted no effect on this parameter in infected cells. The data are discussed from the point of view of a possible influence of hormones on the cholesterol accumulation in cells and on the adenylatecyclase activity in cell membranes.