Hepatic iron in the control of iron absorption in a rat liver transplantation model.

Rat liver transplantation was utilized to study the effect of hepatic iron on the control of iron absorption. Six iron-loaded and six normal livers were transplanted into normal or iron-loaded animals. Iron absorption was measured pretransplant and 10 days posttransplant by total-body counting (59Fe). The animals were loaded with oral carbonyl iron to produce a predominantly parenchymal hepatic iron distribution and with parenteral iron dextran to produce a predominantly reticuloendothelial iron distribution. The carbonyl iron-loaded livers contained 175 +/- 6.6, the iron dextran livers 180 +/- 41, and the normal livers 6.6 +/- 2.8 mumol FE/g dry wt. Iron absorption was unchanged by the insertion of normal livers into normal animals. The transplantation of carbonyl iron-loaded livers into normal animals caused a marked decrease in iron absorption posttransplant from 7.2 +/- 0.9% to 0.3 +/- 0.4% (P less than .001) posttransplant. Neither the transplantation of iron dextran-loaded livers into normal animals nor the transplantation of normal livers into iron-loaded animals significantly altered iron absorption at 10 days posttransplant. These results are consistent with the hypothesis that hepatocyte iron stores are a major determining factor controlling iron absorption.