Effect of Ionizing Radiation on Hæmoglobin and Cytochrome c

Abstract

THE study of the oxygen-effect in ionizing radiation may elucidate the part which indirect effects play in inhibiting biological cell functions through the action of oxidizing radicals and hydrogen atoms, which are formed from water. In continuation of previous work¹ the following substances have been exposed to X-rays: oxyhæmoglobin (HbO₂) in air, hæmoglobin (Hb) in nitrogen, methæmoglobin (Methb) in air and in nitrogen, reduced and oxidized cytochrome c in air and in nitrogen. The concentration of hæmoglobin (in phosphate buffer pH. 6.0) varied between 1.3 × 10⁻⁵ and 3.2 × 10⁻⁴ M and that of cytochrome c (in phosphate buffer pH. 7.3) between 0.8 and 2.0 × 10⁻⁵ M. The X-ray dose varied between 0.8 and 75.0 kr. (190 kVp., no added filtration, dose-rate 4.8 kr./min.). Changes in absorption spectra of the substances examined, which were measured spectro-photometrically, were a measure of the irradiation effect.