EFFECT OF AMINO ACIDS ON UPTAKE OF l‐HISTIDINE BY RAT BRAIN SLICES

Effect of acidic (dicarboxylic) alpha‐amino acids on uptake of L‐histidine by intestinal mucosa, testis, spleen and kidney in vitro: a comparison with effect in brain.

“…Spots derived from the medium after incubation were then compared by eye with those 8-2 derived from the medium before incubation. Alterations in concentration of more than about 25 % were detectable by this means (Neame, 1964).…”

“…The figures presented are the mean and standard deviation (using the formula for small samples), the latter calculated using n = number of tissue samples. (The number of rats involved in each case in experiments other than with brain may be found by dividing n by 2; for experiments with brain, see Neame, 1964.) The water content of the tissue after incubation has been taken as that found already under similar conditions (Neame, 1962).…”

“…The grade and source of amino acids used were those indicated elsewhere (Neame, 1964). The acidic amino acids were neutralized by the addition of an equivalent amount of NaHCO3.…”

“…Paper chromatography was used as described elsewhere (Neame, 1964) to detect any gross change in added amino acid during incubation. In each case a measured sample of the suspending medium before incubation and a further sample of the same medium after incubation were applied to chromatography paper.…”

“…In brain, its uptake can be inhibited by, among others, the acidic (dicarboxylic) a-amino acids, owing to competition for entry into the tissue (Neame, 1964). On the other hand, in intestine in vitro (Agar, Hird & Sidhu, 1956) and in kidney in vivo (Webber, Brown & Pitts, 1961;Webber, 1962), the acidic amino acids have no similar effect, yet in all three tissues mentioned there is no lack of active transport of the acidic amino acids themselves (Stern, Eggleston, Hems & Krebs, 1949; Gibson & Wiseman, 1951;Webber, 1962; Tsukada, Nagata, Hirano & Matsutani, 1963).…”