Functional activity of NADH-dependent reductase system in liver and guerin’s carcinoma microsomal fraction in rats exposed to preliminary irradiation

The activity of liver and Guerin’s carcinoma microsomal NADH-dependent reductase system has been investigated in tumor-bearing rats exposed to preliminary irradiation. Preliminary irradiation of rats (before transplantation of Guerin’s carcinoma) resulted in the decrease of NADH-cytochrome b reductase activity and contents of cytochrome b in the Guerin’s carcinoma microsomal fraction in the logarithmic phases of oncogenesis compared with the non-irradiated tumor-bearing rats. The effect of irradiation preceding transplantation of the tumor to rats results in the increase of enzymatic activities of liver microsomal NADH-cytochrome b reductase in the latent and logarithmic phases of tumor growth as compared with non-irradiated tumor-bearing rats. At the same time the contents of cytochrome b decreases. During longer periods after irradiation the investigated parameters approached to those in the group of non-irradiated tumor-bearing animals.