Effects of insulin-induced hypoglycaemia on the fate of glucose carbon atoms in the mouse

Abstract

[U-14C]Glucose was injected into mice and the distribution of 14C in various chemical fractions of the whole body was determined at times from 15 min. to 8 hr. after injection. At 1 hr. after injection 31.8% of the recovered 14C was found in the expired air and 26.7% was found in the isolated glycogen, lipids, proteins, nucleic acids and in other acid-insoluble carbon compounds ("residual 14C"). The rest (41.5%) was combined in acid-soluble substances. When insulin was injected 5 min. or 1 hr. before injection of [U-14C]glucose, and the mouse was killed 1 hr. later, the 14C content of expired air, glycogen, protein and "residual 14C" was not significantly affected; but the incorporation of 14C into lipids was increased 2- to 3-fold. Chromatography of the lipids on silicic acid columns and by thin-layer chromatography showed that the main effect of insulin injection was to increase the incorporation of 14C into fatty acids. A significant increase of 14C after insulin injection was also found in a glyceride in which the 14c was combined in glycerol.