Heterogeneity of transport systems for L-glutamine in mouse mammary gland.
The characteristics of the transport systems of L-glutamine in lactating mouse mammary gland have been studied. L-glutamine 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. The other two Na+-dependent systems, which we have named BCI(-)-dependent and BCl(-)-independent, are the new systems identified. These are broad specificity systems and were discriminated on the basis of inhibition analysis, Cl- dependency and the effect of preloading mammary tissue with amino acids. While L-aspargine inhibited the uptake of L-glutamine via both these broad specificity systems, L-homoserine inhibited the uptake of L-glutamine via only BCl(-)-dependent system. The uptake of L-glutamine via the BCl(-)-independent system was upregulated by preloading mammary tissue with L-serine, while BCl(-)-dependent system was unaffected. The Na+-independent uptake of L-glutamine was inhibited by 2-aminobicyclo-(2,2,1)heptane carboxylic acid and other neutral amino acids, and identified as the system L.
Sharma
R
R
Division of Animal Biochemistry, National Dairy Research Institute, Karnal, Haryana, India.
Kansal
V K
VK
D000598:Amino Acids, Cyclic / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D005260:Female; D005973:Glutamine / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007774:Lactation / Q000502:physiology; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D009924:Organ Culture Techniques; D012964:Sodium / Q000378:metabolism
D000598:Amino Acids, Cyclic; D005973:Glutamine; C006504:2-aminobicyclo(2,2,1)heptane-2-carboxylic acid; D012964:Sodium