Determination of dependence of spin-lattice relaxation rate in serum upon concentration of added iron by magnetic resonance imaging.
Dependence of spin-lattice relaxation rate (1/T1) in serum upon concentration of added iron was studied in the concentration range 0.0179-0.179 mmol l-1 for each of ferrous and ferric iron. In conjunction with the serum study, 1/T1 in solutions of transferrin and a mixture of albumin and gamma globulin was also studied as a function of added iron concentration. At low concentrations 1/T1 in serum increases linearly with increasing amounts of iron for each ion, and then reaches saturation for ferrous iron, whereas it shows an inflection for ferric iron. To explain the partition of added iron between various serum components, the effect of iron on 1/T1 in serum was compared with those of transferrin and the mixture. This effect can be defined as relaxivity or the incremental increase in relaxation rate per millimolar of added iron. At low concentrations the relaxivities of iron in serum, about 0.91 mmol-1 l s-1 for ferric and 0.95 mmol-1 l s-1 for ferrous ion, approximate well to the relaxivity of iron in transferrin solutions, which was measured to be about 0.92 mmol-1 l s-1. Furthermore, at high concentrations the relaxivity of ferric iron in serum, 0.44 mmol-1 l s-1, becomes similar to that of the mixture which is about 0.39 mmol-1 l s-1. These findings imply that iron added to serum first satisfies the binding requirements of transferrin, and the binding of iron to the other serum proteins occurs at high concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)
Yilmaz
A
A
Department of Clinical Physiopathology, University of Florence, Italy.
Bucciolini
M
M
Longo
G
G
Franciolini
F
F
Ciraolo
L
L
Renzi
R
R
D001769:Blood; D006801:Humans; D066298:In Vitro Techniques; D007501:Iron / Q000097:blood* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008961:Models, Structural; D012709:Serum Albumin / Q000378:metabolism; D012996:Solutions; D014168:Transferrin / Q000378:metabolism; D005719:gamma-Globulins / Q000378:metabolism
D012709:Serum Albumin; D012996:Solutions; D014168:Transferrin; D005719:gamma-Globulins; D007501:Iron