Metabolic turnover of pyridine nucleotides in ascites cells of sarcoma Sa 180 and in the liver tissue of rats before and after ionizing radiation.

Metabolic turnover of NADP+ labeled with 14C in the ribose moiety of their molecules was determined in the ascites cells of sarcoma Sa 180 and in the rat liver tissue. The half-lives of NAD+ and NADP+ in the Sa 180 sarcoma cells were 60 min (NAD+) and 90 min (NADP+) and 120 min (NADP+). Experiments were done on animals to study the time-dependent effect of ionizing radiation on the values of pooled NAD+ and NADP+ after 0.129 C/kg (500 R) and 0.387 C/kg (1500 R) whole-body irradiation, and the metabolic turnover of these nucleotides 5 h after whole-body irradiation with 0.387 C/kg (1500 R). Exposure to 0.129 C/kg (500 R) whole-body irradiation induced no apparent changes compared to the controls. Within 5 h of irradiation the whole-body dose of 0.387 C/kg (1500 R) produced changes in rat liver cells characterized by a reduction of the nucleotide biological half-lives (NAD+ from 80 to 60 min and NADP+ from 120 to 70 min). No such changes in the pyridine nucleotide turnover were detected in Sa 180 ascites sarcoma cells.