AJP - Regulatory, Integrative and Comparative Physiology, Vol 247, Issue 5 842-R849, Copyright © 1984 by American Physiological Society
Quantitation of reticuloendothelial iron kinetics in humans
M. Stefanelli, D. P. Bentley, I. Cavill and H. P. Roeser
Reticuloendothelial iron kinetics were investigated in a simultaneous
dual-isotope study in 10 healthy adult subjects in whom 55Fe-ferric
hydroxide phosphate colloid was used to label the reticuloendothelial iron
pools, and 59Fe-transferrin was used to define plasma iron kinetics. The
simultaneous clearance of 55Fe and 59Fe from plasma and the uptake of each
into red blood cells were measured over 14 days. The 55Fe-colloid was
cleared almost immediately, and its iron was rapidly released to bind to
plasma transferrin. Red cell incorporation of 55Fe was, however, much
slower than that of 59Fe bound to transferrin in vitro. The data were
analyzed by a new model of reticuloendothelial iron metabolism that
contained two reticuloendothelial iron pools; one had a rapid turnover and
donated iron to transferrin, and the other, a storage pool, had a slower
turnover. The transit pool contained a mean of 164 mumol iron with little
variation between subjects, whereas the storage pool was somewhat larger
(mean 873 mumol iron) and showed more marked variation between subjects. In
general an equal proportion of the iron leaving the transit pool went to
transferrin and to the storage pool. The distribution between the two
routes did not appear to be related either to plasma iron concentration,
latent iron-binding capacity, or transferrin saturation.
