Comparison of iron-59, indium-111, and gallium-69 transferrin as a macromolecular tracer of vascular permeability and the transferrin receptor.
Tracer amounts of [59Fe++]citrate, [111In+++]chloride, and [68Ga+++]chloride were complexed with autologous plasma transferrin. Each of these complexes were co-administered with [125I]albumin by i.v. injection and their biodistribution was studied in Wistar rats. The plasma clearance of 59Fe and [125I]albumin was monoexponential with half-times of 49-70 and 277 min, respectively. The plasma clearance of 68Ga and 111In was biexponential with second component half-times of 157 and 232 min, respectively. Indium-111 tissue distribution was similar to that of [125I]albumin in heart, lung, muscle, brain and Walker-256 allograft. Iron-59 distribution spaces were generally the highest of the metal complexes in all tissues except muscle, where the 68Ga space was highest. The effects of transferrin-specific receptor-mediated endocytosis can be avoided in many organs and Walker-256 allografts by using the indium-transferrin complex, and the radiolabeled complex may be a convenient macromolecular tracer to estimate vascular permeability and vessel pore size in tumor and systemic tissue. In contrast, the iron-transferrin complex may be useful for measuring and imaging transferrin-specific receptors in brain and tumor tissue.
Otsuki
H
H
Nuclear Medicine Department, Warren G. Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland.
Brunetti
A
A
Owens
E S
ES
Finn
R D
RD
Blasberg
R G
RG
D000818:Animals; D001932:Brain Neoplasms / Q000000981:diagnostic imaging; D002199:Capillary Permeability; D005710:Gallium Radioisotopes / Q000493:pharmacokinetics; D007205:Indium Radioisotopes / Q000493:pharmacokinetics; D007504:Iron Radioisotopes / Q000493:pharmacokinetics; D008297:Male; D011877:Radionuclide Imaging; D051381:Rats; D011919:Rats, Inbred Strains; D011990:Receptors, Transferrin / Q000032:analysis*; D012709:Serum Albumin / Q000378:metabolism; D014018:Tissue Distribution; D014168:Transferrin
D005710:Gallium Radioisotopes; D007205:Indium Radioisotopes; D007504:Iron Radioisotopes; D011990:Receptors, Transferrin; D012709:Serum Albumin; D014168:Transferrin