Radiorespirometric analysis of glucose metabolism during the feeding with 3'-methyl-4-(dimethylamino)azobenzene in rat

The metabolic fate of the labeled glucose (U-14C) was studied during the feeding with 3'-methyl-4-(dimethylamino)azobenzene(3'-Me-DAB) in rats by the method of radiorespirometry. The peak time (PT) was inclined to hasten from 2nd, reached to the maximum at 4th, and markedly returned to delay at 5th week after the administration of 3'-Me-DAB. The peak height (PH) at 4th to 5th week was lower than that of control. These alterations coincided with the appearance of α-fetoprotein (AFP) at an early stage. However, no marked changes were found in the yield value (YV). The activities of glycolytic enzyme were assayed continuously for 6 weeks after the administration of 3'-Me-DAB. As the result, only hexokinase was activated at 4th week, while pyruvate kinase was inhibited to the level of about 30% of control immediately after the onset of 3'-Me-DAB up to 5th week. Changes of radiorespirometric parameter and enzyme activity were compared no normal and tumor bearing rats. These results were significantly different from those which obtained at an early stage, 1st to 6th week, after the administration of 3'-Me-DAB. Namely, the haste of PT observed at 4th week was not found in tumor bearing rats. On the other hand, the activity of hexokinase was slightly decreased in tumor bearing rats, while the activity of pyruvate kinase was about 2 times as high as that of normal rats. (author)