Effect of X-Radiation upon Succinoxidase of Rat Kidney

Abstract

This expt. was designed to determine whether the reduced 02 uptake by rat tissues following irradiation is due to (1) inhibition of -SH enzymes and not to inhibition of other enzymes concerned with complete oxidation of substrates or (2) failure of the substrate to diffuse as easily in irradiated tissue as in normal tissue. The succinoxidase system, including its component enzymes, was determined in rat kidney homogenates within 2 hrs. after the admn. of 400 r or 800 r total-body X radiation. There was no evidence of inhibition of any of the enzymes. The metabolism of kidney slices from rats exposed to the same doses was studied manometrically with Na succinate and Li py-ruvate substrates. No statistically significant differences could be found between the values for the control and the X-irradiated animals. Results of this expt. indicate that X-ray doses that are high enough to cause hematological changes and death in rats do not cause measurable effects in the metabolism of rat kidney slices nor in the enzyme systems studied, including suc-cinic dehydrogenase. A discussion of the lack of correlation between radiation-induced in vivo and in vitro effects is given.