Effect of Whole Body X-Irradiation of Rats on Net Synthesis of Albumin, Fibrinogen, a,-Acid Glycoprotein, and a,-Globulin (Acute Phase Globulin) by the Isolated, Perfused Rat Liver*

Adult male Sprague-Dawley rats were exposed to whole body x-irradiation. One hour after 900 r and 2000 r and 2, 4, and 6 days after 900 r, their livers were perfused for 6 hours with defibrinated rabbit blood, with L-lysine-l-14C and 250 mg of glucose infused for the first 4 hours. Net synthesis of several specific plasma proteins was estimated by serological measurements of changes in their concentration in perfusate. Net synthesis of albumin was decreased a maximum of 25% 4 to 6 days after 900 r, which was essentially the same as that evidenced by livers from u&radiated rats fasted for 5 days. Net synthesis of fibrinogen, estimated by chemical as well as serological measurements, was about 1.5 times the normal rate 4 days after 900 r. Net synthesis of al-acid glycoprotein was increased at 2,4, and 6 days after 900 r, with approximately 5 times the normal rate at 4 days. Although cr2 (acute phase)-globulin was present at low concentration in the plasma of some irradiated rats at the time of hepatectomy, no evidence was obtained for net synthesis of this protein during perfusion of their livers. Based on the premise that the half-lives of the messenger RNA for rat albumin and fibrinogen are less than 3 hours, our observation that 900 r and 2000 r of whole body x-irradiation failed to suppress synthesis of these proteins is interpreted to mean that x-irradiation in these doses does not damage the DNA of intact rats enough to interfere significantly with transcription of these species of messenger RNA. Perfusions of livers from irradiated rats did not differ from controls with regard to bile secretion, net changes in urea