Inhibition of DNA synthesis in hamster cheek pouch tissue in organ culture by dibutyryl cyclic AMP and a homologous extract

Hamster cheek pouch tissue cultured with 10⁻⁴M dibutyryl cyclic AMP exhibits inhibition of the rate of DNA synthesis. When tissue is cultured with dibutyryl for different time periods throughout the 18 hours of incubation, the effect on the rate of DNA synthesis is very similar. A combination of dibutyryl cyclic AMP and an epithelial cell extract from hamster cheek pouch tissue containing a natural epithelial chalone, appears to have an additive effect on the inhibition of the DNA synthesis rate.