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

AX5-134
Table AX5-8.3 (cont’d). Bone Cell Cultures Utilized to Test Effects of Lead
Compound
Dose/Concentration
Duration Exposure
Route Species Effects Blood Level Reference
Pb acetate
10 −11 to 10 −7 M
3 min
In medium
Pb acetate
0.5 to 60 µM
24 to 48 h
In medium
Pb acetate or Pb
chloride
0.1 to 200 µM
24 h to 6 days
In medium
Rat
Osteosarcoma
Cells
(ROS 17/2.8)
Human
Osteosarcoma
Cells (HOS
TE 85)
and
Rat
Osteosarcoma
Cells
(ROS 17/2.8)
Chick growth
plate
chondrocytes
Treatment of ROS cells with Pb at 1 or 5 µM concentrations produced a rise in [Ca 2+ ] i
to 170 nM and 230 nM, respectively, over the basal level of 125 nM. An elevation in
[Ca 2+ ] i to 210 nM occurred during treatment with an activator of PKC, phorbol 12myristate
13-acetate (10 µM). Pretreatment with a selective inhibitor of PKC,
calphostin C, did not change basal [Ca 2+ ] i, but prevented the Pb-induced rise in [Ca 2+ ] i.
Free Pb 2+ activated PKC in a range from 10 −11 to 10 −7 M, with a Kcat (activation
constant) of 1.1 H 10 −10 M and a maximum velocity (Vmax) of 1.08 nmol/mg/min
compared with Ca activation of PKC over a range of 10 −8 to 10 −3 M, with a Kcat of
3.6 H 10 −7 M, and a Vmax of 1.12 nmol/mg/min.
HOS TE 85 Cells
Inhibition of proliferation (IC 50) = 4 µM Pb
Cytotoxicity = 20 µM Pb
ROS 17/2.8 Cells
Inhibition of proliferation (IC50) = 6 µM Pb
Cytotoxicity = 20 µM Pb
Highest Pb concentration in both cell types found in mitochondrial fraction.
Growth plate chondrocytes were exposed to 3 or 30 µM for up to 6 days. Maximal
inhibition of cell proliferation as measured by thymidine incorporation occurred after a
3-day exposure to Pb. A similar 40% inhibition was found at both concentrations.
Higher concentrations (up to 100 µM) did not produce further inhibition.
In cultures treated for 24 h, Pb produced a dose-dependent inhibition of alkaline
phosphatase, with 10 µM producing maximal inhibition (40–50% inhibition). Effects
of Pb on proteoglycan synthesis were not found until after 48 h of exposure, with
maximal effect after 72 h of exposure (twofold, 30 µM). Pb exposure (10 to 200 µM)
for 24 h produced a dose-dependent inhibition of both type II and type X collagen
synthesis.
Not applicable Schanne et al.
(1997)
Not applicable Angle et al. (1993)
Not applicable Hicks et al. (1996)