Metabolism of putrescine in neuroblastoma and glioma cells during culture.

The metabolism of putrescine in neuroblastoma and glioma cells was analyzed during culture. In the former cells the formation of gamma-aminobutyric acid from putrescine was low and constant during the logarithmic phase and increased dramatically during the stationary phase or in cultures with low serum concentrations, while in the latter cells it was low and constant throughout culture. The formation of spermidine from putrescine in both cell lines was active at days 1-2 of culture and decreased gradually during culture. These findings indicate that spermidine formation is closely related to proliferation of the cells, and gamma-aminobutyric acid formation to differentiation or maturation of the neuroblastoma cells.