1. Guy and Bertha Ireland Research Laboratory, Department of Biochemistry, University of North Dakota Medical School, Grand Forks.

Abstract

SPLEEN and thymus have been found to exhibit a biochemical lesion; namely, uncoupling after they have been exposed in vivo to sub-lethal doses of ionizing radiation^1–5. Hall et al.⁶ have shown that the rate of synthesis of ATP in liver mitochondria was decreased by 20 per cent after irradiation for 1 h and remained at this lower level for 12 h. Florsheim et al.⁷ have shown that in vivo irradiation with 500–800 r. of X-rays did not impair the ability of adult mouse brain to metabolize oxygen. Whole-body irradiation increases plasma phospholipids⁸ and increases the total mitochondria phospholipids, especially the phosphatidyl glycerol fraction⁹. Kennedy¹⁰ and Garbus et al.¹¹ have demonstrated that synthesis of phospholipids occurs in isolated mitochondria and requires the maintenance of oxidative phosphorylation or the addition of ATP. The incorporation of ³⁵S-sulphate into rat brain sulphatides has been investigated¹². The concentration of sulphatides–sulphur in brain is a function of age and the incorporation of the isotope into the sulphalipid takes place only in the young animal^12–14. The synthesis of sulphalipids requires ATP¹⁶. With these observations in mind, experiments were undertaken to determine the effect of whole-body X-irradiation on the uptake of ³⁵S-sulphate into rat brain sulphatides.