Metabolism of glucose, fructose and lactate in vivo in chronically cannulated foetuses and in suckling lambs

Abstract

Chronically cannulated sheep fetuses and suckling lambs were injected with 14C-glucose, fructose or lactate and sequential blood samples taken under conditions of minimal stress and without anesthesia. Gluconeogenesis from lactate was not detectable in fetal sheep, but the pathway was active in suckling lambs. Fructose utilization rates were low in fetal sheep, with no measurable conversion into glucose or lactate. The high rates of irreversible loss of both glucose and lactate in the fetus were decreased in suckling lambs. Radioactivity from 14C-glucose entered both the lactate and fructose pools in fetal sheep and entered the lactate pool in suckling lambs. A model is proposed in which C flow between glucose, fructose and lactate was quantified in fetal sheep.