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The activation of phosphorylase in neonatal rat liver

Cake, M.H.ORCID: 0000-0002-5899-7291 and Oliver, I.T. (1969) The activation of phosphorylase in neonatal rat liver. European Journal of Biochemistry, 11 (3). pp. 576-581.

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The percentage of α-glucan phosphorylase in the active form was measured in the liver of premature rats following surgical delivery. The enzyme is 30% active in the late foetal liver and reaches 45% activation four hours after birth. Thereafter there is a slow decline to the new-born level. Puromycin and actinomycin D injected at delivery are without effect on the enzyme activity and activation of preformed inactive enzyme therefore occurs. These results are interpreted to mean that there is a transitory increase in the concentration of 3′ :5′-cyclic AMP in postnatal rat liver. Glucose and ergotamine tartrate partially inhibit phosphorylase activation when injected at delivery and their effects are additive, implicating hypoglycaemia and hormonal mechanisms in the postnatal activation. Fructose and galactose also inhibit phosphorylase activation while mannose is without effect. Foetal liver phosphorylase is activated in utero by injection of 3′ :5′-cyclic AMP and in postnal rats a transitory increase in phosphorylase activity after injection of the cyclic nucleotide indicates a life time of the injected compound of less than 1 h. These results are discussed in relation to the induction of enzymes in postnatal rat liver by 3′ :5′-cyclic AMP.

Item Type: Journal Article
Publisher: FEBS Press
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