Multicompartmental analysis of iron kinetics in anemic dogs
Koepke, J.A.; Sankaran, S.; Rose, S.D.; Stewart, W.B.
Indian Journal of Medical Research 58(1): 39-55
1970
ISSN/ISBN: 0019-5340 PMID: 5439949 Document Number: 25352
At the same time as 59FeCl3 in 2 mg FeCl3 was given by stomach tube 55FeCl3 mixed with homologous plasma was given by vein to 10 normal dogs. The activity of each radionuclide in plasma and red cell samples collected over the subsequent 7 h was counted using a gas flow method. Each dog was then made anaemic by repeated bleeding and maintained in this condition for 2 to 4 months. The experiment was then repeated. Chronic haemolytic anaemia was then produced in each dog by the repeated injection of acetylphenylhydrazine for several months. The experiment was repeated. The variation of plasma 55Fe activity with time was estimated using a 3-compartment model. Fe was assumed to interchange between a mucosal Fe compartment, plasma Fe and a marrow Fe compartment. The differential equations describing this system were expressed as a function of time containing 2 exponential components and a constant. The plasma 59Fe clearance data were resolved into 2 exponential components and the intercompartmental rates of exchange were estimated from their slopes and intercepts. The volume of each was calculated from the size of the plasma Fe compartment and the appropriate rates of exchange. The total amount of Fe absorbed was calculated from the percentage of 59Fe incorporated in the red cells. Absorption was assumed to be instantaneous and this enabled the concentration of Fe in the mucosal pool to be estimated. Fe deficiency had no effect on the rate of stable Fe transfer from the mucosa to plasma or from plasma to the marrow although the fractional rate of transfer was increased. Haemolytic anaemia increased the movement of Fe from mucosa to plasma and from plasma to marrow. The size of the mucosal Fe compartment was increased in dogs with Fe deficiency and haemolytic anaemia, although the difference was not significant. It is suggested that the changes in the size of the mucosal Fe pool may be related to the mechanism regulating Fe absorption. I. A. J.