Erythrocyte enzymes in experimental lead poisoning

Effects of low-level lead exposure on pyrimidine 5'-nucleotidase and other erythrocyte enzymes. Possible role of pyrimidine 5'-nucleotidase in the pathogenesis of lead-induced anemia.

“…Our observations support those of Rogers et al (27), who did not measure activities of individual glycolytic enzymes but found lactate and C02 production from glucose to be normal in erythrocytes from rabbits with experimentally induced lead poisoning (blood lead levels, 117-+14 ig/100 ml). Our observations regarding malic dehydrogenase, acetylcholinesterase (measured on only three subjects), acid phosphatase, and glucose-6-phosphate dehydrogenase are also in accord with theirs, although their report cites conflicting data on the latter (27). Glutathione content, usually thought to be decreased in lead toxicity (2), was not significantly altered, a finding supported by that of Angle and McIntire (23).…”

“…The latter include variable inhibitions of heme synthetase (24) and of 8-aminolevulinic acid synthetase (24)(25)(26) and dehydratase (25)(26)(27)(28), accounting for the elevated blood and urine concentrations of those intermediates of porphyrin and heme metabolism that are characteristic of lead toxicity.…”

Comparison of in vivo effect of inorganic lead and cadmium on glutathione reductase system and delta-aminolevulinate dehydratase in human erythrocytes.

“…On the contrary, our conclusion that within the Pb-B (and Cd-B) range reported in the present paper no impairment of the glutathione redox system occurs is supported by Saita and Lussana's (1971) clinical follow-up of an occupationally Pbintoxicated woman with erythrocytic G-6-PD deficiency, and by other studies on erythrocytes from Pb-intoxicated workers showing no significant changes in G-6-PD (Mole et al, 1965;Shafer and Tague, 1970) or in glutathione reductase activity (Shafer and Tague, 1970). Similar results were obtained with experimentally lead-poisoned rabbits (Mole et al, 1965;Rogers et al, 1971). In spite of a significant decrease of erythrocytic G-6-PD activity in acute lead-poisoned rats, Erich and Waller (1967) concluded from their own investigations and those of others that the premature splenic sequestration of circulating erythrocytes in lead-intoxication is a consequence of disturbances in the erythrocyte membrane (formation of Pb-complexes with membrane proteins) caused by lead rather than of changes in metabolism.…”

“…Deficiency in one enzyme system, for example G-6-PD, can cause hypersusceptibility to occupational (Granzoni and Rhomberg, 1965;Steiger, 1968;Saita and Lussana, 1971) However, the relationship between ALAD activity of lead-poisoned erythrocytes and their level of endogenous GSH has been interpreted by several authors in different ways: (a) if a control mechanism for ALAD involving GSH exists, it might have been affected in intoxication with lead (de Barreiro, 1969); (b) the lead-induced loss of ALAD activity should scarcely be influenced by the endogenous GSH concentration (Granick et al, 1973); or (c) lead should not act directly on GSH, and the inhibition of ALAD would not be due to reduced levels of GSH Vergnano et al, 1967). Concerning the effects of lead on the activity of erythrocyte G-6-PD (measured in haemolysates) conflicting results have been reported on occupationally lead-intoxicated workers (Rubino et al, 1963;Mole et al, 1965) and on experimentally lead-poisoned animals (Mole et al, 1965;Erich and Waller, 1967;Rogers et al, 1971).…”

Lead poisoning: association with hemolytic anemia, basophilic stippling, erythrocyte pyrimidine 5'-nucleotidase deficiency, and intraerythrocytic accumulation of pyrimidines.

“…Lead affects metabolism at many points, and sideroblastic anemia, disturbed synthesis of hemoglobin, and disordered membrane function have been documented as other end results of the multiple actions of lead (26,(28)(29)(30)(31)(32)(33)(34)(35)(36)(37). Indeed, a heavy metal capable of reacting with the ubiquitously distributed sulfhydryl groups which characterize so many crucial enzymes could hardly fail to produce metabolic aberrations at a multiplicity of loci.…”