582 Xir. HEMOGLOBIN CATABOLISM, II 



Uroporphyrin III if injected is deposited in the same manner as 

 uroporphyrin I {364-', cf., however. Section 3.3.4.). 



3.2.3. Destruction of Porphyrins. Injected uroporphyrin or protopor- 

 phyrin is destroyed to a large extent (Giinther, 1070; Schreus and Carrie, 

 406,34.67; Vigliani, 2882), but some uroporphyrin appears in the urine 

 {1070). If the kidney's perfused with porphyrin solutions, uroporphyrin 

 passes rapidly into the urine, coproporphyrin more slowly and protoporphyrin 

 not at all (Grotepass and Hulst, 1064). Earlier claims of Schreus and Carrie 

 {2467) that protoporphyrin is converted by the liver into bile pigment, have 

 been abandoned by these workers {406). Watson and co-workers {2424,2997) 

 also found no increase of bile pigment in the bile, when the liver of dogs or 

 rabbits was perfused with protoporphyrin solutions, although 98% of the 

 porphyrin disappeared. It has been reported {2137) that normal liver bile, 

 not that of liver damaged by sulfonal, destroys coproporphyrin rapidly. 

 Dobriner {601), however, recovered 70% of injected coproporphyrin I in the 

 bile of fistula dogs, and Vigliani {2882) 50% of coproporphyrin I and 20% 

 of coproporphyrin III in the human fistula bile. Coproporphyrin is thus less 

 readily destroyed than protoporphyrin. The difference in recovery of copro- 

 porphyrins I and III supports the suggestion of Watson {2986) that the former 

 is more readily excreted by the liver. 



3.2.4. Conversions of One Porphyrin to Another. No evidence 

 for conversion of protoporphyrin to uroporphyrin has been found 

 when the former is destroyed in the liver (Schreus and Carrie, 2467; 

 van den Bergh, 229). 



It would be of great importance to know whether protoporphyrin 

 can be converted into coproporphyrin in animal metabolism, but the 

 evidence available can at best be considered as suggestive and has 

 been considerably weakened by more recent experiments. 



As will be seen in Section 3.3.5. there is also no reliable evidence for con- 

 version of protoporphyrin into coproporphyrin by intestinal bacteria. Several 

 workers (Papendieck, 2101; Schumm, 2492,2493,2495,2499,2503,2506; 

 Fischer, 788,793; Brugsch, 365) have observed that meat diet increased 

 coproporphyrin excretion in the urine and Papendieck {2103) that it increased 

 fecal coproporphyrin excretion. According to Fischer and co-workers {832, 

 848), the excretion of coproporphyrin in the urine was increased by injections 

 of protoporphyrin. An increase in the coproporphyrin content of organs as 

 the result of absorption of protoporphyrin from the rectum was claimed by 

 Kammerer and Weisbecker {1455). 



In no instance is there evidence, however, that the coproporphyrin thus 

 formed was of type III. In fact it was apparently considered to be copro- 

 porphyrin I by Fischer {cf. 861, p. 479). In some instances the porphyrin 

 classified as coproporphyrin was probably deutero-, hemato-, or meso- 

 porphyrin. This possibility was suggested later by Fischer himself {832; 

 861, p. 480) in explanation of the increase of "coproporphyrin" excretion 



