Gallium-transferrin as a macromolecular tracer of vascular permeability.
Labeling of plasma transferrin with gallium was investigated to determine whether the gallium-transferrin complex could be effectively used as a macromolecular tracer in studies of capillary permeability using Positron Emission Tomography (PET). Three gallium-plasma preparations were tested and 2 h biodistribution studies were performed in rats. The three preparations gave similar blood clearance and tissue distribution data, but the methods used for evaluating gallium-transferrin binding were found to be suboptimal. Gallium clearance from blood was biexpoential with both components faster than that of 125I-albumin. Gallium distribution spaces in all tissues including intracerebral Walker-256 tumors were larger than those of albumin. These results indicate a relative instability of the gallium-transferrin complex in vivo, which appears to preclude its use as an acceptable radiolabeled protein for vascular permeability studies using PET.
Brunetti
A
A
Department of Nuclear Medicine, N.I.H., Bethesda, MD 20892.
Blasberg
R G
RG
Finn
R D
RD
Larson
S M
SM
D000818:Animals; D001932:Brain Neoplasms / Q000000981:diagnostic imaging; D002199:Capillary Permeability; D002279:Carcinoma 256, Walker / Q000000981:diagnostic imaging; D002951:Citrates; D019343:Citric Acid; D009368:Neoplasm Transplantation; D051381:Rats; D011919:Rats, Inbred Strains; D012711:Serum Albumin, Radio-Iodinated; D014018:Tissue Distribution; D014055:Tomography, Emission-Computed; D014168:Transferrin / Q000493:pharmacokinetics*
D002951:Citrates; D012711:Serum Albumin, Radio-Iodinated; D014168:Transferrin; D019343:Citric Acid