Morphological, pharmacokinetic, and hematological studies of lead-exposed pigeons

Abstract

Adult white Carneaux pigeons were orally dosed with inorganic lead (6.25 mg Pb/kg/day, gastric intubation) for up to 64 weeks and the following studies were carried out: (1) the subcellular distribution of lead in erythrocytes; (2) the changes in tissue lead levels with time; (3) morphological assessment of tissue responses to lead; and (4) hematological effects of lead, the major systemic evidence of toxicity. In the early stage of exposure, there is some lead accumulation in the erythrocyte nucleus relative to its proportion of total cell volume, but such accumulation disappears with time. The kinetic behavior of lead in seven tissues—blood, brain, kidney, liver, femur, sciatic nerve, and crop—was seen to conform to two mathematical methods of lead distribution; brain, kidney, and femur lead increased with dosing time and reached or appeared to approach an upper plateau; lead in blood, liver, sciatic nerve, and crop increased to a maximum, followed by a decline to a lower plateau level. Morphologically, renal tubule cells showed the presence of lead-containing inclusion bodies while CNS mitochondria appeared to have accumulated lead. No evidence of segmental demyelination was seen. Lead exposure induced a marked and rapid hypochromic normocytic anemia in these birds, as well as an elevation in erythrocyte porphyrin. No disturbance in mechanical fragility or osmotic resistance was noted.