PHARMACOLOGY AND TOXICOLOGY OF PORPHYRINS 601 



It is, however, still unexplained why these toxic effects are not 

 found in chronic porphyria, or, if found, at least occur far less 

 strongly. 



There is a suspicion that porphyrins are carcinogenic agents 

 (Figge and co-workers, 751,753,lk2Jf; Strong, 2689).* 



3.5.3. Physiologic Action. Hematoporphyrin has been used thera- 

 peutically by Huhnerfeld (775,1358) in nervous depressions and 

 melancholia. He observed that it depressed blood calcium and 

 increased hemopoiesis (cf. also 370). Two milligrams daily for four- 

 teen days did not produce any damage U06). Klliver (1552) found 

 that hematoporphyrin was not taken up by the white matter of 

 rabbits, which normally contained some porphyrin (1551), but was 

 accumulated in the pituitary gland. 



According to Hinsberg and co-workers (1287,1289,1290) injections 

 of proto- and hematoporphyrins increase protein metabolism and 

 raise the secretion of melanophore-dispersing hormone from the 

 pituitary in rabbits, and cause premature follicle formation in mice 

 ovaries. 



Based on their discovery that porphyrins other than protopor- 

 phyrin can competitively inhibit the formation of respiratory enzymes 

 from protoporphyrin in Hemophilus influenzae, Granick and Gilder 

 (1035) have advanced the interesting hypothesis that these por- 

 phyrins may be of physiologic importance as regulators of the forma- 

 tion of respiratory enzymes and of the consumption of oxygen. 



* Cf., however, Bittner and Watson {28-3a). 



