Abstract
The effect of glucagon on gluconeogenesis from lactate in the presence of high concentrations
of albumin-bound fatty acids has been studied in the isolated perfused livers of starved
rats. Simultaneously, ketone formation has been measured.
In the presence of either 1 mM oleic acid or 1.5 mM octanoate, basal gluconeogenesis
was stimulated by the same degree (+75%). In contrast, ketone formation from octanoate
exceeded that from oleic acid by about 100%. Thus, a rate of ketogenesis beyond that
obtained with oleic acid was not accompanied by a further increase in glucose formation.
Simultaneous addition of glucagon with either oleic acid or octanoate resulted in
the same additive stimulation of gluconeogenesis. This supports the view of different
mechanisms of action of fatty acids and glucagon on gluconeogenesis.
Glucagon, in the presence of oleic acid, gave rise to an additive stimulation of ketogenesis,
while, on the other hand, no further increase in ketogenesis was observed together
with octanoate. This indicates a dissociation of the gluconeogenetic and ketogenetic
action of glucagon.
Key words
Isolated Perfused Liver - Gluconeogenesis - Ketogenesis - Fatty Acids - Glucagon
1 * Present address: Medizinische Universitätsklinik, D 78 Freiburg, Hugstetter Str.
(Germany)
