The utilization of nucleotides by the mammal. VI. Purine nucleotides totally labeled with C14 in mice bearing sarcoma 180.

The incorporations into nucleic acids of adenosine-3′-phosphates, labeled in both base and sugar with C14, have been studied in the tumorbearing mouse. When compared with data obtained in the rat, these results indicate that there was a more extensive utilization of the adenylic acid but the utilization of guanylic acid was about the same as in the rat. Guanylic acid is utilized by the mouse to a greater extent than is guanine, but the differential between the two is not so marked as that in the rat. The extensive transpurination involved during the incorporation of the guanine of guanylic acid into RNA guanine was of the order observed in the rat. The incorporations into the tumor nucleic acids were approximately one-tenth to one-fifth of those into the visceral nucleic acids, in line with the now common observations that exogenously supplied purine derivatives are not utilized extensively in tumor tissues.