Cyclic nucleotides and their associated enzymes in 9,10-dimethyl-1,2-benzanthracene-induced mammary tumors of rats.

A comparison is presented of the levels of cyclic adenosine 3 :5 -monophosphate, cyclic guanosine 3 :5 -monophosphate (cyclic GMP), adenylate cyclase, guanylate cyclase, cyclic adenosine 3 :5 -monophosphate phosphodiesterase, and cyclic GMP phosphodiesterase in 9,10dimethyl-1,2-benzanthracene-induced mammary tumors of rats and in mammary glands from virgin and midpregnant rats. Many changes were observed, but the differ ences are difficult to interpret since the changes were not consistent when the data were expressed on a per mg protein, RNA, DMA, and wet tissue weight basis. For example, cyclic adenosine 3 :5 -monophosphate levels in tumor tissues were elevated relative to tissues from midpregnant animals when the data were expressed on a per mg protein, RNA, or wet tissue weight basis, but when the data were expressed on the basis of DNA content there was no difference. Cyclic GMP levels were not different in tumor tissues versus those from midpregnant animals when the data were expressed on the basis of RNA content or wet tissue weight, but the level of cyclic GMP was significantly less in the tumor tissues when the data were expressed on the basis of protein and DNA content. Adenylate cyclase activity was generally ele vated in tumor tissues versus those from virgin or midpregnant animals. Guanylate cyclase activity was the same in tumor tissues versus those from midpregnant animals except when the data were expressed on the DNA content; then the enzyme activity was about 50% less in the tumor tissues. When the data were based on RNA content or wet tissue weight, the activities of the phosphodiesterases were generally higher in the tumor tissues versus those from virgin or midpregnant animals. On the basis of protein or DNA content, phosphodiester ase activities were equivalent to or less than those in the tumor tissues versus mammary glands from virgin or midpregnant rats.