title: Na+-dependent transport of basic, zwitterionic, and bicyclic amino acids by a broad-scope system in mouse blastocysts.
abstract: Mouse blastocysts which had been activated from diapause in utero appeared to take up amino acids via a Na+-dependent transport system with novel characteristics. In contrast to other cell types, uptake of 3-aminoendobicyclo [3,2,1]octane-3-carboxylic acid (BCO) by blastocysts was largely Na+ dependent. Moreover, L-alanine and BCO met standard criteria for mutual competitive inhibition of the Na+-dependent transport of each other. The Ki for each of these amino acids as an inhibitor of transport of the other had a value similar to the value of its Km for transport. In addition, both 2-aminoendobicyclo [2,2,1]heptane-2-carboxylic acid (Ki approximately 1.0 mM) and L-valine (Ki approximately 0.10 mM) appeared to inhibit Na+-dependent transport of alanine and BCO competitively. Finally, alanine and L-lysine appeared to compete for the same Na+-dependent transport sites in blastocysts. For these reasons, we conclude that lysine, alanine, and BCO are transported by a common Na+-dependent system in blastocysts. In addition, the apparent interaction of the system with other basic amino acids, such as 1-dimethylpiperidine-4-amino-4-carboxylic acid, which has a nondissociable positive charge on its side chain, and L-arginine and L-homoarginine, whose cationic forms are highly predominant at neutral pH, suggests that the cationic forms of basic amino acids are transported by the wide-scope system.
mesh_terms: D000409:Alanine / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism* / Q000494:pharmacology; D000598:Amino Acids, Cyclic; D000599:Amino Acids, Diamino / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001755:Blastocyst / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D007700:Kinetics; D008239:Lysine / Q000378:metabolism; D051379:Mice; D008813:Mice, Inbred ICR; D011247:Pregnancy; D012964:Sodium / Q000494:pharmacology*; D014316:Tritium
chemical_list: D000596:Amino Acids; D000598:Amino Acids, Cyclic; D000599:Amino Acids, Diamino; D014316:Tritium; C039361:3-aminobicyclo(3.2.1)octane-3-carboxylic acid; D012964:Sodium; D008239:Lysine; D000409:Alanine