Radiogallium localization in tumors: blood binding and transport and the role of transferrin

Journal Article · Tue Jul 01 00:00:00 EDT 1980 · J. Nucl. Med.; (United States)

OSTI ID:5061095

Vallabhajosula, S R; Harwig, J F; Siemsen, J K; Wolf, W

As a crucial step toward the understanding of the tumor localization of gallium, we have re-investigated its binding and transport in blood. The studies were performed in vivo by injection of gallium-67 citrate in rabbits, and in vitro by incubation of gallium-67 citrate with individual plasma proteins. By ultrafiltration and gel filtration chromatography, rabbit plasma samples showed essentially complete protein binding, whereas dialysis indicated considerable nonprotein-bound gallium, the amount depending on the dialysis medium. According to electrophoresis, total binding was inversely proportional to electrophoresis time. Affinity chromatography showed all gallium to be bound to transferrin, whereas electrophoresis caused continuous dissociation of gallium from transferrin, with the resulting unbound radioactivity appearing in various other protein bands. Similarly, the binding of gallium to transferrin in the in vitro incubation studies was inversely proportional to electrophoresis time, whereas ultrafiltration and gel filtration chromatography showed all gallium to be transferrin-bound. No binding of gallium to other proteins, such as albumin, was observed. This study demonstrates that gallium at the tracer level in blood is exclusively bound to and transported by transferrin, and indicates that electrophoresis and dialysis of easily dissociable metal complexes are subject to significant artifacts. Accurate determination of protein binding of radiopharmaceuticals requires a combination of analytical techniques and cautious interpretation of the results.

• Research Organization: Univ. of Southern California, Los Angeles
• OSTI ID: 5061095
• Journal Information: J. Nucl. Med.; (United States), Vol. 21:7
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
59 BASIC BIOLOGICAL SCIENCES
BLOOD PLASMA
CPB
GALLIUM 67
BIOLOGICAL LOCALIZATION
NEOPLASMS
RADIONUCLIDE KINETICS
TRANSFERRIN
CHROMATOGRAPHY
DIALYSIS
ELECTROPHORESIS
EXPERIMENTAL DATA
RABBITS
TIME DEPENDENCE
ULTRAFILTRATION
ANIMALS
BETA DECAY RADIOISOTOPES
BIOLOGICAL MATERIALS
BLOOD
BODY FLUIDS
DATA
DAYS LIVING RADIOISOTOPES
DISEASES
ELECTRON CAPTURE RADIOISOTOPES
FILTRATION
GALLIUM ISOTOPES
GLOBULINS
GLOBULINS-BETA
INFORMATION
INTERMEDIATE MASS NUCLEI
ISOTOPES
MAMMALS
MATERIALS
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PROTEINS
RADIOISOTOPES
SEPARATION PROCESSES
VERTEBRATES
560172* - Radiation Effects- Nuclide Kinetics & Toxicology- Animals- (-1987)
550201 - Biochemistry- Tracer Techniques