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Metabolism of leucine by the isolated perfused goat udder

Published online by Cambridge University Press:  01 June 2009

Eddy Roets ,
Anne-Marie Massart-Leën ,
Georges Peeters  and
Roger Verbeke
Eddy Roets
Affiliation:
Department of Physiology, Veterinary Faculty of the University of Ghent, Casinoplein 24, B-9000 Ghent, Belgium
Anne-Marie Massart-Leën
Affiliation:
Department of Physiology, Veterinary Faculty of the University of Ghent, Casinoplein 24, B-9000 Ghent, Belgium
Georges Peeters
Affiliation:
Department of Physiology, Veterinary Faculty of the University of Ghent, Casinoplein 24, B-9000 Ghent, Belgium
Roger Verbeke
Affiliation:
Laboratory of Chemical Analysis of Food of Animal Origin, Veterinary Faculty of the University of Ghent, Casinoplein 24, B-9000 Ghent, Belgium
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Summary

Seven lactating goat mammary glands from 6 goats were perfused for several hours in the presence of [U-14C]L-leucine (4 experiments) or [2-3H; l-14C]DL-leucine (3 experiments) and received adequate quantities of glucose, acetate and amino acids. Radioactivity in casein was mainly recovered in leucine and 90% of casein leucine was derived from free plasma leucine. About 64% of the leucine molecules were used for casein synthesis. Up to 12% of the molecules were channelled into lipid synthesis, while the remaining (up to 24%) were metabolized to CO2. From the 3H/14C ratio of casein and casein leucine, it was calculated that 70–80% of the leucine molecules were reversibly transaminated before their incorporation into milk protein. However, only 4–8% of the plasma leucine molecules were transaminated during passage through the udder. Different pools for oxidation and for protein synthesis may be present in the goat mammary gland.

Type
Original Articles
Information
Journal of Dairy Research , Volume 50 , Issue 4 , November 1983 , pp. 413 - 424
Copyright
Copyright © Proprietors of Journal of Dairy Research 1983

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