The uptake of amino acids by carrot slices

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Abstract
Conditions determining uptake of amino acids by slices of carrot have been investigated. Slices of carrot take up amino acids from the medium and establish a large concentration gradient in favor of the tissue. The process of uptake of both D- and L-isomers is inhibited by 2,4-dinitrophenol and by cyanide. The process, therefore, requires energy from respiration. The rate of uptake of L-histidine was greater than that of D-histidine, although for phenylalanine, valine and leucine there was usually no significant difference between amounts of the optical isomers taken up during 5 hr. The inorganic salts potassium chloride and potassium phosphate (solutions at pH 6.0-8.0) inhibited uptake of L-histidine. L-histidine and L-arginine mutually inhibit the uptake of each other.