Summary
Using the model of the in vitro non-recirculating perfused rat liver we studied kinetic
aspects of the hepatic handling of glucagon. Under conditions of a 20 min glucagon
infusion (glucagon mass flows of 0.05, 0.46 and 4.75 ng/g liver/min, respectively) according to a rectangular profile both total and individual glucagon
extractions were dependent on mass flow and time. The time course of glucagon extraction
started with an acute phase within the first minute of infusion with a maximum value
of 70%, which decreased within the following 30 sec by more than 40%. Depending on
concentration, there was a progressive decrease in the hepatic extraction of glucagon
up to the end of perfusion. Hepatic glucagon degradation was found to take place only
at a little extent. Immediately after terminating the hormone infusion, the liver
changed over into a glucagon-releasing organ. Kinetics of glucagon infusion and glucagon-induced
hepatic glycogenolysis did not distinguish by parallelism but rather by phase shifting.
Key words
Glucagon - Rat Liver Perfusion - Glucagon Degradation - Glucagon Extraction
