Effect of Whole-body X-irradiation on Plasma-protein Synthesis: Role of Adrenals

Summary

In rats exposed to whole-body x-irradiation (800 R), the changes in plasma concentrations and glycine-1-¹⁴C incorporation into albumin, fibrinogen and total plasma proteins were followed for 6 days. In intact rats, the relative synthesis rate of fibrinogen showed two peaks at 3 hours and 4 days after irradiation (166 and 654 per cent of controls). In adrenalectomized and irradiated rats, this biphasic response was abolished and only a plateau was observed between 3 hours and 4 days. Adrenalectomized rats also showed a sharp rise in albumin synthesis 3 hours after irradiation. Thereafter, though it decreased progressively, it was more than that of adrenalectomized-unirradiated rats. The first peak (at 3 hours) of albumin and fibrinogen synthesis in adrenalectomized rats appears to be due to factors other than corticosteroids. Further, it appears that corticosteroids may not be the prime factors responsible for the elevated plasma protein synthesis in intact rats after irradiation. Since the magnitude of increase is more in intact than in adrenalectomized rats, these hormones seem to play a contributory role in plasma-protein anabolism.