VPT 421: Veterinary Toxicology (2+0)

MECHANISM OF TOXICITY

• Lead produces toxicity by inhibiting certain enzymes having free sulphydryl groups. This inhibition is particularly noted with the precursors of haeme and leads to a decrease of haeme synthesis with resultant anaemia.
• Lead poisoning is characterized by accumulation of protoporphyrin IX and non-haeme iron in red blood cells, accumulation of aminolevulinate in plasma and increased excretion of aminolevulinate.
• Lead also inhibits haeme synthetase, which is required for incorporation of iron in the haeme molecule.
• It also prevents the entry of iron from cytosol to mitochondria.