Thyroid hormone-induced changes in gluconeogenesis and ketogenesis in perfused XXXX liver.

@entity844 @entity6212 @entity3952 @entity1378 @entity412 @entity880 @entity35
The regulation of ketogenesis and gluconeogenesis was studied in isolated, perfused livers from hyper- and euthyroid @entity35 . Experimental conditions were varied with respect to @entity880 and @entity844 concentration in the perfusion medium and with respect to the nutritional state of the @entity35 . 1. The rate of uptake of @entity3952 in perfused livers was independent of the thyroid and nutritional states of the animals. 2. In livers from 48-h-fasted @entity35 no difference was found in rates of ketogenesis between the euthyroid and @entity1378 livers except when 10 mM @entity880 was present in the perfusate. In recently fed @entity35 the rates of ketogenesis from @entity3952 (1 mM) and endogenous substrates were low in euthyroid livers (0.45 and 0.05 mumol/min per g liver, respectively), while these rates in @entity1378 livers were (1.333 and 0.136 mumol/min per g liver, respectively). With @entity6212 as substrate, high rates of ketogenesis were found in recently fed livers from both euthyroid and @entity1378 @entity35 (1.573 and 1.717 mumol/min per g liver, respectively). 3. Without @entity3952 in the perfusion medium the rate of gluconeogenesis from low (1 mM) @entity880 concentrations in livers from 48 h-fasted- @entity35 was slightly increased in the @entity1378 state (0.548 mumol/min per g liver) compared to the euthyroid state (0.408 mumol/min per g liver). When @entity880 concentration in the perfusion medium was raised to 10 mM the rate of gluconeogenesis was increased 4-fold in the @entity1378 livers (1.800 mumol/min per g liver) but only 20% in the euthyroid livers (0.490 mumol/min per g liver). The presence of @entity3952 (1 mM) had no effect on the rate of gluconeogenesis from low @entity880 concentrations in livers form 48-h-fasted animals of either thyroid state. At 10 mM @entity880 the inclusion of @entity3952 caused a pronounced stimulation of gluconeogenesis in euthyroid livers (from 0.490 to 1.766 mumol/min per g liver) but not in @entity1378 livers (from 1.800 to 1.973 mumol/min per g liver) so that the difference in the rate of gluconeogenesis between the two thyroid states disappeared. 4. The content of endogenous substrates was measured in liver biopsies taken before perfusion. The glycogen concentration was independent of the thyroid state in 48-h fasted animals. The @entity412 content was independent of the thyroid state in recently fed animals. In recently fed animals the glycogen content was reduced by 90% in @entity1378 animals, and in 48-h-fasted animals the @entity412 content was reduced by 50% in @entity1378 animals. 5. The energy cost of gluconeogenesis from @entity880 appeared to be independent of the thyroid state.
