Effect of tin on porphyrin biosynthesis.

Certain disturbances in porphyrin biosynthesis were examined in rabbits administered with either tin or lead. Stannous chloride treatment increased the concentrations of coproporphyrin in blood and urine, as did lead acetate treatment. No effect of tin on 5-aminolevulinic acid concentration was observed in blood and urine, whereas lead treatment increased it markedly in both. Tin profoundly inhibited the activity of 5-aminolevulinate dehydratase in blood, but did not alter it in liver although tin content in liver was considerably higher than that in blood. In contrast to a prolonged inhibition of erythrocyte 5-aminolevulinate dehydratase by lead, tin inhibition of erythrocyte 5-aminolevulinate dehydratase activity was rapidly reversed after the cessation of the metal treatment.