Abstract

A. El-Waseef and M. M. Ei-Sharabasy

The activities of heme pathway enzymes have been measured in rabbits with subacute lead, mercury and cadmium-intoxications. Delta-aminolevulinic acid synthesis (ALA-S) was assined in the liver, delta-aminilevulinic acid dehydratase (ALAD), uroporphyrinogen synthetase (URO-I-S), porphobilinogenase (PBG-ase) and uroporphyrinogen decarboxylase (URO-D) were assayed in erythrocytes and ferrochelatase was assayed in leucocytes. A simple method {or the Isolation of good yield of leucocytes from blood and a modification of the assay method of ferrochelatase are described. Both ALA-S and BPG-asa are activated by lead and mercuny and not affected by cadmium, ALAD is inhibited by lead and mercury in the order lead mercury while it is less inhibited by cadmium. URO-I-S la not affected by the three metals.$ URO-D is inhibited by the three metals in the order cadium > mercury > lead, and ferrochelatase Is inhibited by both lead and mercury and not affected by cadrrium. The present results are parallel with the disorders in porphyrin metabolism reported in our previous work. The results are discussed with special emphasis on the role of the inhibition of ferrochelatase on the preceding enzyme-catalysed steps of the heme pathway .

Heme; Pathway; Cadmium

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