Abstract
The effect of cycloserine, isonicotinic acid hydrazid, pyridoxal, 2-methyl-4-amino-5-hydroxymethylpyrimidine, and desoxypyridoxine on the heme biosynthesis in rat hone marrow was studied by using radioisotope Fe^<55>. 1) The incorporation of Fe^<55> into heme in vitamin B_6 deficient rats increased proportionally to increase in the amount of vitamin B_6 administered with the diet. The incorporation increased also in vitro by the addition of pyridoxal to the reaction system of vitamin B_6 deficient group. 2) Cycloserine, isonicotinic acid hydrazid, and desoxypyridoxine inhibited the incorporation of Fe^<55> into heme in vitro. The inhibitions could not be restored by pyridoxal. 3) The incorporation of Fe^<55> into heme was smaller in the rat administered with cycloserine, compaired with the control and it could not be restored by pyridoxal. 4) 2-Methyl-4-amino-5-hydroxymethylpyrimidine increased the incorporation of Fe^<55> in vitro.
