Characteristics of transport systems of L-alanine in mouse mammary gland and their regulation by lactogenic hormones: evidence for two broad spectrum systems.
The characteristics of the transport systems of L-alanine in lactating mouse mammary gland and their regulation by lactogenic hormones have been studied. L-alanine uptake was mediated by three Na(+)-dependent and one Na(+)-independent systems. The 2-(methylamino)isobutyric acid-sensitive component of Na(+)-dependent uptake exhibited the usual characteristics of system A. Cl- dependency has been established for system A. The other two Na(+)-dependent systems, which we have named BCl(-)-dependent and BCl(-)-independent, are described for the first time. These are systems with broad specificity and were distinguished on the basis of inhibition analysis, Cl- dependency and the effect of preloading mammary tissue with amino acids. The Na(+)-independent route was identified as system L, which operates independent of Cl-. The A, L and BCl(-)-independent transport systems were upregulated in pregnant mouse mammary tissue cultured in vitro in the presence of lactogenic hormones (insulin plus cortisol plus prolactin). Insulin alone also upregulated systems A and L to some extent in pregnant mouse mammary tissue. BCl(-)-dependent activity was not detected in pregnant mouse mammary tissue and was not induced by lactogenic hormones in vitro.
Sharma
R
R
Division of Animal Biochemistry, National Dairy Research Institute, Karnal, Haryana, India.
Kansal
V K
VK
D000409:Alanine / Q000378:metabolism*; D000596:Amino Acids / Q000494:pharmacology; D000598:Amino Acids, Cyclic; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002712:Chlorides / Q000494:pharmacology; D046508:Culture Techniques; D005260:Female; D006854:Hydrocortisone / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007328:Insulin / Q000494:pharmacology*; D007700:Kinetics; D008321:Mammary Glands, Animal / Q000378:metabolism*; D051379:Mice; D011388:Prolactin / Q000494:pharmacology*; D012964:Sodium / Q000494:pharmacology; D015091:beta-Alanine / Q000031:analogs & derivatives / Q000494:pharmacology
D000596:Amino Acids; D000598:Amino Acids, Cyclic; D002712:Chlorides; D007328:Insulin; D015091:beta-Alanine; C012924:2,2-dimethyl-beta-alanine; C006504:2-aminobicyclo(2,2,1)heptane-2-carboxylic acid; D011388:Prolactin; D012964:Sodium; D000409:Alanine; D006854:Hydrocortisone