Hormonal Control of Amino Acid Transport in the Liver of Rats Exposed to Whole-Body γ Irradiation

• Published in: Radiation research 1978-02, Vol.73 (2), p.360-372
• Main Authors: Kilberg, Michael S., Neuhaus, Otto W.
• Format: Article
• Language: English
• Subjects: Amino acids; Amino Acids - metabolism; Aminoisobutyric Acids - metabolism; Animals; Biological Transport - radiation effects; Blood; Blood plasma; Corticosterone - blood; Cyclic AMP - metabolism; Diabetes Mellitus, Experimental - metabolism; Gamma Rays; Glucagon - blood; Glucagon - metabolism; Growth Hormone - blood; Growth hormones; Hormones; Insulin; Insulin - blood; Insulin - pharmacology; Irradiation; Liver; Liver - metabolism; Liver - radiation effects; Male; Perfusion; Rats; Space life sciences; Whole body irradiation
• ISSN: 0033-7587; 1938-5404
• DOI: 10.2307/3574827

Whole-body exposure of rats to γ rays led to a degeneration of tissue proteins and a concomitant elevation in blood amino acids. Simultaneously there was a stimulated uptake of amino acids by the liver and a state of gluconeogenesis and glycogenesis. It has now been established that these events were accompanied by increases in both blood glucagon and insulin levels. Growth hormone and corticosterone were not affected. Although both glucagon and insulin stimulate amino acid transport, the former was primarily responsible for the elevated transport in the liver following whole-body irradiation. The primary role of glucagon was demonstrated by the radiation-induced uptake of N-methyl α-aminoisobutyric acid, a model amino acid whose hepatic transport was previously shown to be affected by glucagon and not by insulin. Confirmatory evidence was obtained by showing that exogenous insulin actually inhibited the radiation-induced uptake of α-aminoisobutyric acid and N-methyl α-aminoisobutyric acid by the isolated perfused liver. Furthermore, the radiation syndrome was accompanied by elevated hepatic concentrations of cyclic AMP.