Hymenolepis diminuta: Na + -Dependent and Na + -Independent Components of Neutral Amino Acid Transport

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Abstract
The effect of incubation in Na+-free and ouabain-containing solutions on uptake of amino acids by H. diminuta was examined for the amino acids Ala, Met, Val, Gly, Leu and .alpha.-aminoisobutyric acid. Uptake of Ala, Met, Val and Gly were all dependent on external Na+ and were all inhibited by 1.0 mM ouabain when using tissue slices. The influx of amino acids exhibiting a Na+-dependent component was observed in a reversed Na+-K+ gradient. Sources of energy other than ion gradients may be involved in the uptake of the amino acids examined. The Na+-independent component of amino acid uptake was pH sensitive and was stimulated at pH 6 where the zwitterionic species is most prevalent.