Air Quality Criteria for Lead Volume II of II - (NEPIS)(EPA) - US ...

AX5-181
Table AX5-10.8. Lead and Intestinal Uptake—Effect on Ultrastructure, Motility, Transport, and Miscellaneous
Compound and
Concentration Duration Species Blood Lead Effects a Authors
Pb acetate, 0.1%, in
drinking water
100 mg/Pb acetate/kg
b. wt.
Added Pb concentration
in the milk—0–80 µg/mL
Pb as Pb acetate, for 0.5–
10.0 µM, Zn as Zn
acetate 0, 5, 10, or 50 µM
Temperature variation
Expts, 5 µM Pb, and
incubated for 10 min at 4,
22, or 37 ° C
Multiple analyses at
2, 30, and 60 days
after Pb exposure
Multiple analyses at
2, 30 and 60 days
Male Wistar rats — Small intestinal goblet cells are involved in Pb detoxification.
Pb treatment for 30 days produces characteristic goblet cells in the
intestine and Pb appears in conjunction with goblet cell membrane.
Prolonged exposure to Pb more than 30 days caused silver sulphide
deposition (indicative of heavy metal deposition) in the mucus droplets
of cytoplasmic goblet cells.
Male Wistar rats — Pb poisoning changes the ultra structure of intestine.
— Adult and Infant
rats (16 days)
Fresh or frozen rat
or Avian milk
5, 10, 30 or 60 min,
Simultaneously with
Pb for 10 min
Incubation time
10 min
IEC-6 normal rat
intestinal
epithelial cells
30 days Pb exposed rat intestinal enterocytes showed numerous, small
rough-membraned vesicles and prominent, dilated golgi complexes, in
their cytoplasm.
By 60 th day, Pb-exposed rats had a vacuolated cytoplasm and prominent
golgi filled with vacuoles.
— 90% of Pb in rat and bovine milk was found associated with caseine
micelles regardless of whether the milk is labeled in vitro or in vivo with
203 Pb. Similarly Pb in infant milk formula was also predominantly
associated with casein, however, to a much lower extent than rat and
bovine milk formulae.
Pb tracer studies indicated that in infant rats, as the milk traversed through
the intestine, in the collected luminal fluid, Pb was primarily associated
with casein curd and remained as a nonprecipitable, nondialyzable fraction
as it moved to the small intestine, indicating that Pb remains with protein
fraction as it traverses through the stomach and small intestine fraction.
— Pb uptake by IEC-6 cells depends on the extracellular Pb concentration.
Pb transport in IEC-6 cells is time and temperature dependent, involves
sulphahydryl groups, and is decreased by the presence of Zn.
Tomczok et al.
(1988)
Tomczok et al.
(1991)
Beach and Henning
(1988)
Dekaney et al.
(1997)