RGD Reference Report - Effect of glucagon on phenylalanine metabolism and phenylalanine-degrading enzymes in the rat. - Rat Genome Database
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Effect of glucagon on phenylalanine metabolism and phenylalanine-degrading enzymes in the rat.

Authors: Brand, LM  Harper, AE 
Citation: Brand LM and Harper AE, Biochem J. 1974 Aug;142(2):231-45.
RGD ID: 5128604
Pubmed: (View Article at PubMed) PMID:4155291

Glucagon administered subcutaneously to rats for 10 days had no significant effect on liver phenylalanine hydroxylase activity, but induced liver dihydropteridine reductase more than twofold. In rats administered a phenylalanine load orally, glucagon treatment stimulated oxidation and depressed urinary phenylalanine excretion. These responses could not be related to an effect of glucagon on hepatic tyrosine-alpha-oxoglutarate aminotransferase activity. Even in rats with phenylalanine hydroxylase activity depressed to 50% of control values by p-chlorophenylalanine administration, glucagon treatment increased the phenylalanine-oxidation rate substantially. Although hepatic phenylalanine-pyruvate aminotransferase was increased tenfold in glucagon-treated rats, glucagon treatment did not increase urinary excretion of phenylalanine transamination products by rats given a phenylalanine load. Glucagon treatment did not affect phenylalanine uptake by the gut or liver, or the liver content of phenylalanine hydroxylase cofactor. It is suggested that dihydropteridine reductase is the rate-limiting enzyme in phenylalanine degradation in the rat, and that glucagon may regulate the rate of oxidative phenylalanine metabolism in vivo by promoting indirectly the maintenance of the phenylalanine hydroxylase cofactor in its active, reduced state.


Gene Ontology Annotations    

Biological Process

Objects Annotated

Genes (Rattus norvegicus)
Qdpr  (quinoid dihydropteridine reductase)

Additional Information