Inhibition of hormone-stimulated hepatic glycogenolysis by fructose (Fru) has been attributed to accumulation of the competitive inhibitor Fru1P and/or to the associated depletion of the substrate phosphate (P i ). To evaluate the relative importance of either factor, we used the Fru analogue 2,5-an
Insulin-dependent inhibition of hepatic glycogenolysis by gastric inhibitory polypeptide (GIP) in perfused rat liver
โ Scribed by H. Hartmann; R. Ebert; W. Creutzfeldt
- Publisher
- Springer
- Year
- 1986
- Tongue
- English
- Weight
- 354 KB
- Volume
- 29
- Category
- Article
- ISSN
- 0012-186X
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โฆ Synopsis
The effect of porcine gastric inhibitory polypeptide on hepatic glycogen metabolism was investigated in the isolated in situ perfused rat liver. Glycogenolysis was stimulated by infusion of glucagon into the portal vein (half maximal effective portal vein concentration -30 pmol/1). When glucagon was infused at a final portal vein concentration of 0.5 nmol/1, simultaneous addition of insulin inhibited the glucagon-dependent glycogenolysis in a dose-dependent way (half maximal effective concentration for insulin about 2 nmol/1). Gastric inhibitory polypeptide alone at a concentration of 1 nmol/1 reduced glucagon-dependent glycogenolysis only slightly. However, when infused simultaneously at low insulin concentrations (0.1 nmol/1), gastric inhibitory polypeptide suppressed hepatic glucose production dose-dependently up to 70%. The data suggest that gastric inhibitory polypeptide exerts direct metabolic effects on hepatic glycogen metabolism predominantly in a situation where insulin is simultaneously present, e.g. following ingestion of glucose.
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