The regulation of Na(+)-dependent anionic amino acid transport by the rat mammary gland.
The regulation of anionic amino acid transport, using radiolabelled D-aspartate as a tracer, by rat mammary tissue explants has been examined. Na(+)-dependent D-aspartate uptake by mammary tissue increased between late pregnancy and early lactation and again at peak lactation but thereafter declined during late lactation. In contrast, the Na(+)-independent component of D-aspartate uptake by mammary explants did not change significantly with the physiological state of the donor animals. Premature weaning of rats during peak lactation markedly decreased Na(+)-dependent D-aspartate uptake by mammary tissue. In addition, premature weaning also reduced the effect of reversing the trans-membrane Na(+)-gradient on the fractional loss of D-aspartate from mammary tissue explants. Unilateral weaning of rats during peak lactation revealed that milk accumulation per se reduced the Na(+)-dependent moiety of D-aspartate uptake by mammary tissue suggesting that the transport of anionic amino acids is regulated to match supply with demand. Treating lactating rats with bromocryptine reduced D-aspartate uptake by mammary tissue explants suggesting that the transport of anionic amino acids by the rat mammary gland is regulated by prolactin.
Millar
I D
ID
Hannah Research Institute, Ayr, UK.
Shennan
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DB
D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D001971:Bromocriptine / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism; D005260:Female; D018698:Glutamic Acid / Q000378:metabolism; D007774:Lactation; D008321:Mammary Glands, Animal / Q000187:drug effects* / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D011247:Pregnancy; D011388:Prolactin / Q000494:pharmacology; D051381:Rats; D012964:Sodium / Q000494:pharmacology*; D027981:Symporters; D015854:Up-Regulation
D002352:Carrier Proteins; D008565:Membrane Proteins; D027981:Symporters; D001224:Aspartic Acid; D001971:Bromocriptine; D018698:Glutamic Acid; D011388:Prolactin; D012964:Sodium