Disturbances in heme biosynthesis in rabbits after administration per os of low doses of tin or lead.

The experiment was performed on female rabbits that received per os equimolar doses (17 microM Me/kg) of SnCl2 x 2 H2O or Pb (CH3 COO)2 every day for 5 d. The activity of delta-aminolevulinic acid dehydratase (ALA-D) in the whole blood, liver, kidneys, brain, spleen, and bone marrow, concentration of free erythrocyte protoporphyrins (FEP), activity of delta-aminolevulinic acid synthetase (ALA-S) in the liver and bone marrow, urine delta-aminolevulinic acid (ALA-U), and coproporphyrins (CP-U) were determined. Lead and tin concentrations in the blood were estimated. Lead caused a significant inhibition of ALA-D in the blood, increased FEP concentration, and ALA and CP excretion in urine of rabbits. Lead also decreased ALA-D activity in the bone marrow and in the liver, and did not change ALA-S activity in the liver and bone marrow. Tin did not change any of the examined indices. Tin doses applied in the present study, maintained within the limits of permissible standards of metal levels in human diet, did not affect the process of heme biosynthesis in rabbits.