Lysine uptake by mammary gland tissue from lactating sows

Kinetic properties and substrate specificity of the lysine transport system in porcine mammary gland were studied using mammary tissue explants from nine lactating sows. Sodium dependence of lysine uptake was determined by replacing sodium in the medium with choline. Kinetic parameters of lysine upt...

Full description

Saved in:
Bibliographic Details
Published in:Journal of animal science 2000-02, Vol.78 (2), p.391-395
Main Authors: Hurley, W. L, Wang, H, Bryson, J. M, Shennan, D. B
Format: Article
Language:English
Subjects:
Amino acids
Animal productions
Animal reproduction
Animals
Biological and medical sciences
Biological Transport
Choline - metabolism
Female
Fundamental and applied biological sciences. Psychology
Hogs
Lactation
Lysine - pharmacokinetics
Mammary Glands, Animal - metabolism
Proteins
Sodium - metabolism
Swine - metabolism
Terrestrial animal productions
Vertebrates
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Kinetic properties and substrate specificity of the lysine transport system in porcine mammary gland were studied using mammary tissue explants from nine lactating sows. Sodium dependence of lysine uptake was determined by replacing sodium in the medium with choline. Kinetic parameters of lysine uptake were determined using lysine concentrations from 5 microM to 5.12 mM. Competition of lysine uptake by other amino acids was determined using the cationic amino acids, arginine and ornithine, and using other essential amino acids. Transport of lysine was time-dependent and was unaffected by replacing sodium with choline. Lysine uptake occurred by a transport mechanism with a Km of approximately 1.4 mM and a Vmax of 7.9 mmol x kg cell water(-1) x 30 min(-1). Lysine uptake was inhibited by arginine and ornithine and by high concentrations of L-alanine, L-methionine, L-leucine, cycloleucine, and D-lysine, but not by 2-(methylamino)-isobutyric acid. This transport mechanism is the primary system responsible for uptake of cationic amino acids in lactating sow mammary tissue. The relatively high Km, compared with physiological blood concentrations of lysine, indicates that the kinetic properties of the lysine transport system should not be limiting to milk protein synthesis. Transmembrane transport of lysine by lactating sow mammary tissue should be a direct function of plasma concentrations. However, interactions of other amino acids with the uptake system may affect lysine uptake.
ISSN:0021-8812
1525-3163
0021-8812
DOI:10.2527/2000.782391x