Gluconeogenesis in Vivo from Glycine in X-irradiated Rats

Summary

Gluconeogenesis in vivo from glycine-2-¹⁴C was estimated in x-irradiated (600 R) rats, by measuring the uptake of radioactivity in blood sugar and liver glycogen. The responses obtained have been compared with those in cortisone- and insulin-treated animals.

The incorporation of radioactivity in blood sugar and liver glycogen was high at all time-intervals studied in cortisone-treated rats, both in fasted and glucosefed conditions, showing enhanced gluconeogenesis. Insulin-treated rats, on the other hand, presented an exactly converse picture, indicating reduced formation of new glucose from the ¹⁴C-precursor.

The effect of x-irradiation was different from that of either of these hormones. There was reduced ¹⁴C incorporation in liver and muscle glycogen, while blood sugar showed an increased isotope uptake. Experiments with D-glucose-U-¹⁴C did not indicate, however, any effect in respect of the turnover of glucose. These findings did not suggest an enhancement in the net synthesis of the sugar in ^x-irradiated rats, that could be correlated with the involvement of glucocorticoids.