ENDOGENOUS PORPHYRIN METABOLISM 



579 



phyrin present in the food as such. A scheme of porphyrin metab- 

 oHsm is given in Figure 1. 



Synthesis 



III 



I.III 



Hemoglobin 



III? 



General circulation 



Destruction <- 



Liver 



Bile 



Intestine 



Kidney 



reabsorption 



/ 



Food 



Urine 



Bacteria 



(hematin) 



Fig. 1. Endogenous porphyrin metabolism. 



The amounts of porphyrins that can be found in the animal body 

 under normal conditions are so small that the study of porphyrin 

 metabolism is mainly based on the study of porphyrins in disease. 



3.2.2. Distribution of Porphyrins in the Human Body. Por- 

 phyrin in erythrocytes. The presence of protoporphyrin in erythro- 

 cytes was demonstrated by van den Bergh and co-workers (229) and 

 has been confirmed by many investigators {223 ,79i,lJf.51 ,1631 ,23^7 , 

 2It.eJt,2Jt.96a,2508, 2850, 2883). Normal erythrocytes contain 2-20 Mg- 

 per 100 ml*; the much higher values reported by Lageder (1631) are 

 probably erroneous. The porphyrin is protoporphyrin IX, identical 

 with that of the prosthetic group of hemoglobin (Grotepass, 1061). 



Watson and Clarke (2993; cf. also Grotepass, 1061,161^0) and Bur- 

 mester (383) assumed that reticulocytes were the cells which contained 

 protoporphyrin. This was later partly withdrawn (2991a, 299 J^),a.ilev 

 Keller and Seggel (1505,1996,2526, cf. US) demonstrated that the 



* Cartwright and co-workers Hl3) find 20-50 ^g. per 100 ml. 



