Effect of Vitamin B 12,Folic Acid,and Nicotinamide on Urinary Coproporphyrin Excretion in Photosensitized Rabbits. ∗

Abstract

Summary and Conclusions

The administration of large amounts of folic acid inhibited the increase of the urinary coproporphyrin in rabbits given Rose Bengal and exposed to ultraviolet light. The administration of small amounts of vit. B₁₂ had the same effect. The combination of folic acid and vit. B₁₂ had no advantage over either substance given separately. The administration of nicotinamide in large amount produced a significant but only partial inhibition.

In view of the fact that nicotinamide, folic acid, and vit. B₁₂ are all intimately related to cellular metabolism, it seems highly likely that the marked increases of urinary coproporphyrin under these experimental conditions are likewise so related, but whether to the metabolism of the bone marrow, or some other system of cells is not clear. Further studies of these relationships are in progress.