Abstract
Using a non-recirculating perfusion system, we studied the time course of ketone body output from the isolated rat liver in response to various hormones and changes in pH and redox state. The release of 3-hydroxybutyrate (3-OHB) started to be suppressed within 1 min after the addition of insulin (50 mU/ml) and kept half of the basal level even 10 min after its cessation. The addition of glucagon (0.2 μM) caused an increase in both 3-OHB and acetoacetate (AcAc) outputs from fed livers within 5 min, which reached about 150% of the basal level 10 min after the infusion and maintained a constant level through out the experiment. Growth hormone (2 μ/ml) elicited a slight but significant increase in AcAc output soon after the infusion. Epinephrine (10 μM) also caused a slight increase in both AcAc and 3-OHB outputs 9 min after the infusion and maintained a significant increase even 10 min after stopping infusion. The decrease in pH of the perfusate or the addition of ascorbic acid abruptly suppressed the AcAc production. In summary, the present study clearly demonstrated the direct effects of various hormones on ketogenesis in the liver and the usefulness of a non-recirculating liver perfusion system as a tool for the study of ketogenesis.
