1. Succinate-cytochrome c reductase activity in rat liver decreased to about 60% of the control value after a single injection of cobalt or in a steady state of intoxication, but the activity in the spleen was unaltered. 2. Incorporation of radioactive glycine and 5-aminolevulinate into heme of the liver was markedly inhibited by cobalt treatment. 3. 5-Aminolevulinate synthase [EC 2.3.1.37] activity in the liver decreased to 40% of the control value 4 hr after cobalt injection, and completely recovered 20 hr later. Phenylhydrazine-induced 5-aminolevulinate synthase activity in the spleen was not decreased by cobalt injection. 4. Porphobilinogen synthase [EC 4.2.1.24] activity in the liver decreased and reached its minimum value (42% of the control) 12 hr after cobalt injection. On the other hand, the activity in the spleen showed a marked increase 24 hr after coblat injection. 5. Ferrochelatase [EC 4.99.1.1] activity in the liver was essentially unaltered by cobalt treatment, while the activity in the spleen was elevated dramatically after 24 hr. 6. Concentrations of cobalt after a single injection were about 0.3 mM and 0.03 mM in the liver and spleen, respectively. 7. Inhibitions of 5-aminolevulinate synthase and porphobilinogen synthase activities by cobalt in vitro were not as marked as expected from in vivo experiments.
Effect of cobalt on heme biosynthesis in rat liver and spleen. Publishing Authors By Initials
