Metabolic Interactions of Glucose, Acetoacetate and Insulin in Mammary- Glad Slices of Lactating Rats

1.Utilisation of 5mM- glucose by slices of lactating mammary gland was decreased 33% on addition of acetoacetate (2mM) to the incubation medium. This inhabitation was accompanied by increases in the intracellular concentrations if citrate and glucose 6-phosphate. 2.In the presence of acetoacetate the accumulation of pyruvate in the medium approximately doubled. 3.Insulin completely reversed the inhibitory effect of acetoacetate on glucose utilisation, without altering the amount of acetoacetate removed or pyruvate formed. 4.Similar results were obtained with mammary -gland slices from diabetic rats, except that insulin did not completely reverse the effects of the acetoacetate. 5. Acetoacetate inhibited the formation of 14CO2 [1-14C]pryuvate; this effect was not overcome by insulin. 6. Insulin increased the proportion of [3-14C] acetoacetate that was converted into lipid and decreased that oxidized to CO2. 7. The physiological significance of these findings is discussed.