Enzymes of Glucose Formation and Turnover in X-irradiated Rats

Summary

Profiles of liver enzymes involved in deamination of amino acids, gluconeogenesis and the hepatic turnover of glucose, have been examined for 7 days after whole-body exposure of rats to 600 R of x-rays. Aspartate aminotransferase, serine dehydrase and phosphopyruvate carboxykinase activities were enhanced, though maximal effect was observed on different days after x-irradiation, suggesting a chronological order of events. Fructose-1, 6-diphosphatase and glucose-6-phosphotase did not, however, seem to be affected. Glucose-ATP phosphotransferase and glycogen phosphorylase showed immediate reduction and enhancement, respectively, in their activities, though normal levels were restored within a day after irradiation and were maintained throughout the period under investigation. These results, while indicating no evidence for increase in the net synthesis of glucose, suggested that variations in the enzyme activities could be due to physiological adaptations following a flux of substrates.