ABSTRACT
Metalloporphyrins exert a variety of effects on diverse physiological processes and enzyme systems. Metalloporphyrins inhibit heme oxygenase (1,2), block the effects of metabotropic glutamate receptor activation (3), inhibit long-term po tentiation (4,5), inhibit the allosteric activation of soluble guanylate cyclase (6), and repress hepatic б-aminolevulinate synthase (7). Metalloporphyrins have been administered for the therapy of neonatal hemolytic disease or hyperbilirubine mia (8,9). In lead poisoning, lead interferes with the incorporation of iron into heme and zinc then replaces iron to form zinc protoporphyrin IX (10). Zinc pro toporphyrin IX measured in whole blood fluorimetrically is considered a reliable indicator of the severity of lead poisoning. Elevations of zinc protoporphyrin IX concentrations also occur in patients suffering from iron deficiency anemia and erthyropoietic porphyria (10).
