METABOLISM OF IRON BY NORMAL AND IRON DEFICIENT RAINBOW-TROUT

Fe metabolism in normal and Fe deficient rainbow trout was studied after i.p. injection of 59Fe. In both groups of the 59Fe was absorbed from the peritoneal cavity within 24 h and equilibrium between the plasma 59Fe pool and that of the tissues was attained 8 days after i.p. injection. Liver Fe, the main storage pool in trout, was reduced from the control level of 185 .mu.g/g to < 100 .mu.g/g 16 days after bleeding, whereas, splenic Fe stores were unaffected. In Fe deficient fish the RBC [red blood cell] 59Fe content increased to 70-80% of the injected dose by day 16 compared to 50% in controls. This was attributed to the difference in reticulocyte count which was 10-20% for the bled fish and 2-3% in controls. Some Fe accumulated by erythrocytes is temporarily stored as non-heme Fe by these cells. An average of 15% of the i.p. injected 59Fe was taken up by hepatic tissue of control fish and remained there throughout the 30 day study. In Fe deficient trout liver 59Fe was reduced from a high of 15% on day 2 to < 1% of the initial dose by day 16 post bleeding. There was essentially no detectable loss of 59Fe in the urine or feces of either normal control or Fe-deficient fish.