[Glucagon degradation in the in vitro recycling perfused rat liver during acute energy deficiency].

Hepatic glucagon degradation was studied using recycling perfused livers from 24h fasted rats in the absence of glucose. In comparison with normoxic conditions, a significantly reduced glucagon cleavage was observed within the first 30 min of hypoxic perfusion (acute energy deficiency). On the contrary, glucagon degradation was markedly increased after 30 min. At the same time, increased release of intracellular glucagon-degrading activity occurred. Partial characterization of the degrading activity showed high specificity for glucagon. Both its metal- and thiol-dependent activity and immunological reaction against specific antibodies are characteristic of the insulin-glucagon-proteinase (IGP) of rat liver. These results indicate that a substantial part of the liver-bound glucagon is internalized via an energy-dependent step followed by degradation by IGP.