Characteristics of L-glutamine transport by lactating mammary tissue.
The transport of L-glutamine by the lactating rat mammary gland has been investigated using rat mammary tissue explants and the in situ perfused rat mammary gland. L-glutamine uptake by both explants and the perfused mammary gland was via both Na(+)-dependent and Na(+)-independent pathways. It appeared that these pathways are situated on the blood-facing aspect of the mammary gland. L-glutamine uptake by both mammary preparations was markedly inhibited by 2-aminobicyclo[2,2,1]heptane-2-carboxylic acid in the absence of external Na+. This is consistent with L-glutamine uptake via system L. The Na(+)-dependent component(s) of L-glutamine uptake remains to be precisely identified. However, system A can be ruled out on the basis that L-glutamine was not inhibited by (methylamino)isobutyric acid. Mammary tissue concentrates L-glutamine with respect to both milk and plasma: we suggest that the Na(+)-dependent component(s) of L-glutamine uptake is responsible for generating the intracellular to extracellular concentration gradient.
Calvert
D T
DT
Hannah Research Institute, Ayr, UK.
Kim
T G
TG
Choung
J J
JJ
Burns
C
C
Shennan
D B
DB
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D005260:Female; D005973:Glutamine / Q000378:metabolism*; D007700:Kinetics; D007774:Lactation / Q000378:metabolism*; D008321:Mammary Glands, Animal / Q000378:metabolism*; D009924:Organ Culture Techniques; D010477:Perfusion; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000494:pharmacology; D015091:beta-Alanine / Q000031:analogs & derivatives / Q000494:pharmacology
D005973:Glutamine; D015091:beta-Alanine; C012924:2,2-dimethyl-beta-alanine; D012964:Sodium