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Characterisation of the routes of methionine transport in mouse mammary glands.
Article Dans Anglais | IMSEAR | ID: sea-23380
ABSTRACT
The sites of methionine uptake by mammary glands from late pregnant and lactating mice were studied in vitro. Using the specific A system inhibitor, N-(methylamino) isobutyric acid (MeAIB) and the specific L system inhibitor, 2-amino-bicyclo (2.2.1) heptane 2-carboxylic acid (BCH), we have defined four modes of methionine entry into these tissues. (i) A sodium-dependent A system with a Vmax of 13.4 and 18.8 n mol/g cells/min in pregnant and lactating mice, respectively. This mode of entry was completely inhibited by MeAIB and its Km value was similar (0.45 mM) in both groups. (ii) A sodium-dependent mode with a Vmax of 6.7 and 12.4 n mol/g cells/min and a Km of 0.24 and 0.46 mM in pregnant and lactating mice, respectively. This mode of entry was insensitive to inhibition by MeAIB, and was similar to the ASC (alanine, serine, cysteine) system in other tissues. (iii) A sodium-independent L system with a Vmax of 13.8 and 30.0 n mol/g cells/min and a Km of 0.27 and 0.46 mM in pregnant and lactating mice, respectively. This mode of entry was completely inhibited by BCH. (iv) A sodium-independent non-specific entry amounting to 25 per cent of the total entry at 0.1 mM external methionine which was not inhibited by high concentration of BCH. The results of our studies show an increase in the number of active carriers of the A, ASC and L systems of methionine uptake in mammary glands of mouse during lactation.
Sujets)
Texte intégral: Disponible Indice: IMSEAR (Asie du Sud-Est) Sujet Principal: Transport biologique / Femelle / Lactation / Grossesse / Bêta-Alanine / Acides aminés / Acides aminés cycliques / Animaux / Glandes mammaires animales / Méthionine langue: Anglais Année: 1993 Type: Article

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Texte intégral: Disponible Indice: IMSEAR (Asie du Sud-Est) Sujet Principal: Transport biologique / Femelle / Lactation / Grossesse / Bêta-Alanine / Acides aminés / Acides aminés cycliques / Animaux / Glandes mammaires animales / Méthionine langue: Anglais Année: 1993 Type: Article