564 XI. HEMOGLOBIN CATABOLISM, I 



that the "easily detachable iron" of the erythrocytes plays this role 

 has been disproved. 



Moore and co-workers found the plasma iron low in iron deficiency 

 (c/. also 2180) and during rapid hemoglobin synthesis, and high in 

 aplastic anemia and in relapse in pernicious anemia, when hemo- 

 globin synthesis is considered as being retarded. The level is, how- 

 ever, not always passively controlled by the rate of hemoglobin syn- 

 thesis in the bone marrow. McKibbin and co-workers (1820) found 

 high plasma iron levels associated with rapid regeneration of hemo- 

 globin, and concluded that an active principle in the liver mobilizes 

 the storage iron; this is assumed to be impaired by liver damage. 

 The level of the plasma iron must be considered as a composite effect 

 regulated by the balance of iron absorption from the gastrointestinal 

 tract, mobilization of iron from the body reserves, and formation of 

 iron by hemoglobin breakdown on the one hand, and hemoglobin 

 synthesis and storage of iron in liver and spleen on the other; the 

 excretion of iron plays only an insignificant role (1350,24.09) ; except 

 during growth, the tissue iron (hematin enzymes and myohemoglobin) 

 can be considered as fixed (Fig. 1). 



HEMOGLOBIN 



breakdown 



synthesis tissue iron 



absorption > PLASMA IRON — > excretion 



mobilization 



storage 



STORES 



Fig. 1. Plasma iron. 



Heilmeyer and Plotner (1221) assumed that the breakdown of hemoglobin 

 was of no importance with regard to plasma iron. This was based on experi- 

 ments with StUwe (1222) who showed that plasma iron decreased in sepsis; 

 the evidence for increased hemolysis in sepsis is, however, doubtful, since the 

 total urobilinogen excretion is not increased (cf. Section 9.2A.). Phenyl- 

 hydrazine (4ll,2iS'44) causes a strong increase of the plasma iron //( vivo. 

 The increase of plasma iron resulting from intracorpuscular hemoglobin 

 breakdown in standing blood has been discussed in Section 5. The decrease 



