1979 Volume 28 Issue 3 Pages 151-156
75Se-Selenomethionine is often used for the isotope scanning of pancreas. However, it is desired to develop excellent pancreas scanning agents that give more specific distribution and less radiation hazards than the agent. Pancreas has a high ability to incorporate amino acids into its cells and to utilize the acids for the synthesis of proteins and enzymes. On the basis of this preferential uptake of amino acids, radioactive iodine-labeled amino acids and peptides, γ-131I-iodo-a-aminobutyric acid, N-2-131I-monoiodoacetyl-L- and D-leucines, L- and D-leucine 2-131I-iodoethyl esters, 125I or 131I-labeled dipeptides, and insulin 125I-A and 131I-B chains, were prepared and assayed for their distribution in mouse organs and Ehrlich ascites tumor cells. Radioactivity of these labeled compounds incorporated into pancreas was almost the same as that of liver and spleen, and considerably smaller than that of stomach, duodenum and kidney. Since a high incorporation into stomach was seen also after the administration of 125I-sodium iodide, it was suggested that iodine ions were liberated in vivo from the labeled compounds within a short time.