Increase of ?-Aminolevulinic Acid Dehydratase (ALAD) in rat erythrocytes in lead poisoning

Abstract

The well known fact that the activity of delta-aminolevulinic acid dehydratase (ALAD: EC 4.2.1.24) is reduced in red cells of animals with lead poisoning was found to be upset, by using a modified method of Gibson's original procedure, for determination of activated ALAD activity. The modified method involves addition of 0.2 mM Zn2+ and then preheating the enzyme solution at 60 degrees C for 5 min before following Gibson's original procedure. With this methodological modification, the ALAD activity of erythrocytes of rats poisoned with lead was found increased. Furthermore, the enzyme was purified from the peripheral blood of lead-poisoned rats. ALAD protein in peripheral blood was also determined by single radial immuno diffusion using rabbit anti-serum raised against rat liver ALAD. As the result, the ALAD activity obtained from the modified method was found to be directly proportional to the absolute amount of enzyme proteins determined both by chemically and immunochemically. The modified method for measuring true ALAD content in blood cells in lead poisoning is more reliable than previous ones.

Reduction of myeloid suppressor cell derived nitric oxide provides a mechanistic basis of lead enhancement of alloreactive CD4+ T cell proliferation

“…This dimerization is dependent upon the cofactor heme (as reviewed in (Aktan, 2004)). It has long been known that Pb impairs heme synthesis by blocking the action of δ-aminolevulinic acid dehydratase (ALAD) (Goldstein et al, 1975;Kajimoto et al, 1983;Sharma et al, 2000). Furthermore, induction of heme-oxygenase-I (HO-1) may be a contributing factor to lowered heme levels in certain cell types (Cabell et al, 2004;Opanashuk et al, 1995;Vargas et al, 2003).…”

Effects of lead and/or zinc exposure during the second stage of rapid postnatal brain growth on delta-aminolevulinate dehydratase and negative geotaxis of suckling rats

“…This result contrasts with the increase in blood ALA-D activity in rats exposed to lead acetate during the second stage of rapid postnatal growth (6). In fact, both a reduction and an increase in blood ALA-D activity in lead-exposed rodents have been reported (7,11,12). The studies that report an increase in blood ALA-D elicited by lead exposure have attributed it to an increase in ALA-D synthesis (11,12).…”

“…In fact, both a reduction and an increase in blood ALA-D activity in lead-exposed rodents have been reported (7,11,12). The studies that report an increase in blood ALA-D elicited by lead exposure have attributed it to an increase in ALA-D synthesis (11,12). The group exposed to lead + zinc did not exhibit any decrease in blood ALA-D activity.…”

“…ALA-D activity in erythrocytes is currently the most sensitive indicator of human exposure to lead (1). However, divergent results have been reported for ALA-D activity in the blood of lead-exposed animals, with data showing a reduction (7) or an increase (6,11,12). Mammalian ALA-D has the peculiarity of having zinc as its cofactor (13).…”

“…Mammalian ALA-D has the peculiarity of having zinc as its cofactor (13). It has been demonstrated that zinc, as well as DL-dithiothreitol (DTT) in vitro, is able to restore the lead-inhibited ALA-D activity in rat and human blood (1, [12][13][14]. In addition, an antagonistic effect of zinc on the inhibition of ALA-D by lead in vivo has been reported (15), as well as the absence of an antagonistic effect (16).…”