Conversion of Glucose- 14 C(UL) to 14 CO 2,14 C-Glycogen,and 14 C-Fatty Acids in the Partially Hepatectomized Rat

Abstract

Summary

Partially hepatectomized (67%) rats and sham-operated controls were injected with glucose-¹⁴C(UL) at various times postoperative from 1 hr to 1 week and the expired ¹⁴CO₂ and CO₂ was measured for 3 hr. At the end of the radiorespirometry procedure, plasma free fatty acids, glucose, cholesterol, and ¹⁴C-lipids were determined. Fatty acids, ¹⁴C-fatty acids, nonsaponified ¹⁴C-lipids, glycogen, and ¹⁴C-glycogen were determined in liver. Glycogen and ¹⁴C-glycogen were also determined in muscle. Upon partial hepatectomy plasma free fatty acids increased while glucose and cholesterol decreased. The cumulative percentage of recovery of ¹⁴CO₂ decreased in the partially hepatectomized rat during the first hour of the radiorespirometry period. However, no significant difference between the partially hepatectomized rats and the sham-operated controls was noted at the end of the 3-hr radiorespirometry period. The specific activity of the expired CO₂ was increased in the partially hepatectomized rats because of their decreased CO₂ production. The specific activity of muscle glycogen was decreased in the partially hepatectomized rats while liver glycogen showed an increase which is interpreted to mean the turnover of muscle glycogen is decreased while the turnover of liver glycogen is increased. The recovery of liver ¹⁴C-fatty acids and nonsaponified ¹⁴C-lipid was decreased, indicating that a decreased conversion of glucose to acetyl CoA occurs in the partially hepatectomized rat. The effect of isotopic dilution resulting from a difference in plasma glucose levels between the two groups of rats is discussed.