title: Transport of amino acids into the oestrogen-primed uterus. Enchancement of the uptake by a preliminary incubation.
abstract: 1. Preincubation of the immature rat uterus under physiological conditions was found to increase its subsequent ability to transport alpha-aminoisobutyric acid, l-proline, l-alanine and 1-aminocyclopentanecarboxylic acid. Uptakes of l-valine, l-phenylalanine and l-leucine were not affected. With alpha-aminoisobutyric acid, a doubling of the uptake could be obtained after a 3-5h preincubation period. Uteri from oestradiol-primed rats gave increases similar to those found in tissues from untreated animals. In both cases the preincubation increased the V(max.) of alpha-aminoisobutyric acid uptake but did not affect the K(m). 2. The conditions during the preincubation period determined the increase in subsequent uptake of alpha-aminoisobutyric acid. No increase in uptake was found if the preincubation was carried out at 1 degrees C, in the presence of cyanide or dinitrophenol, under anaerobiosis or with a concentration of puromycin that depressed incorporation of l-leucine into protein by 95%. The puromycin was also shown to prevent the increase in V(max.) normally found after the preincubation period. In addition, no increase was found if Na(+) was omitted from the preincubation medium. Other inorganic ions had smaller effects. 3. The uptake of alpha-aminoisobutyric acid by uteri before and after a preincubation period showed the same general patterns of sensitivity to competitive inhibitors, K(+), pH, temperature and 2,4-dinitrophenol. 4. The results suggest that the preincubation leads to an increase in a protein component of the ;A system' for amino acid transport in the uterus, and that metabolic energy is required for the reactions involved.
mesh_terms: D000409:Alanine / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism*; D000621:Aminoisobutyric Acids / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D004140:Dinitrophenols / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007930:Leucine / Q000378:metabolism; D010649:Phenylalanine / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology; D011392:Proline / Q000378:metabolism; D051381:Rats; D012964:Sodium / Q000494:pharmacology; D013997:Time Factors; D014599:Uterus / Q000187:drug effects / Q000378:metabolism*; D014633:Valine / Q000378:metabolism
chemical_list: D000596:Amino Acids; D000621:Aminoisobutyric Acids; D004140:Dinitrophenols; D010649:Phenylalanine; D004958:Estradiol; D011392:Proline; D012964:Sodium; D007930:Leucine; D014633:Valine; D000409:Alanine; D011188:Potassium