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

AX5-132
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 glutamate
5–20 µM
48 hr
In medium
Pb
0.5 to 5 µM
40 min
In medium
Pb nitrate
5 H 10 −4 to 5 H 10 −15 M
24 h
In medium
Pb acetate
2 to 200 µM
72 h
In medium
Rat
Osteosarcoma
Cells
(ROS 17/2.8)
Rat
Osteosarcoma
Cells
(ROS 17/2.8)
Rat
Osteosarcoma
Cells
(ROS 17/2.8)
Rat
Osteosarcoma
Cells
(ROS 17/2.8)
Cells treated with 0, 5, 10, or 20 µM Pb acetate for 24 h, followed by an additional
24 h exposure to 0 or 100 pg of 1,25-dihydroxyvitamin D 3 and continued Pb 2+
exposure, resulted in a significant (p < 0.05 or less) reduction of osteocalcin secretion,
both in the presence and absence of 1,25-dihydroxyvitamin D 3 at all Pb 2+
concentrations. This effect is not mediated by PKC.
1 and 5 µM Pb 2+ significantly increased [Ca 2+ ] i in the absence of 1,25dihydroxyvitamin
D 3 and significantly reduced the peak elevation in [Ca 2+ ] i induced
by 1,25-dihydroxyvitamin D3.
Simultaneous treatment of previously unexposed cells to Pb 2+ and 1,25dihydroxyvitamin
D3 produced little reduction in the 1,25-dihydroxyvitamin D 3induced
45 Ca uptake, while 40 min of treatment with Pb 2+ before addition of 1,25dihydroxyvitamin
D3 significantly reduced the 1,25-dihydroxyvitamin D 3-induced
increase in 45 Ca influx.
Osteocalcin secretion significantly reduced below control values by culture with 1 µM
Pb 2+ in the presence or absence of added 1,25-dihydroxyvitamin D 3 or 1,25dihydroxyvitamin
D 3 and IGF-I. Inhibition of osteocalcin secretion was almost
complete in either hormone-stimulated or basal cultures with the addition of 100 µM
Pb 2+ . Cellular alkaline phosphatase activity paralleled those of osteocalcin, though
there was no response to IGF-I alone or in combination with 1,25-dihydroxyvitamin
D 3. Pb 2+ at 10 −15 , 10 −12 , and 10 −9 to 10 −7 M did not influence DNA contents of cell
cultures, but 1 µM significantly (p < 0.05) inhibited basal cultures and those with IGF-
I + D3. Cell cultures exposed to 1,25-dihydroxyvitamin D 3 and Pb 2+ were inhibited at
10 µM Pb 2+ .
Pb (2 to 200 µM) had no effect on cell number or DNA and protein synthesis.
Alkaline phosphatase activity was significantly reduced (p < 0.001) by Pb in a dose-
and time-dependent manner.
Pb Concentration. Alkaline Phosphatase Inhibition
2 µM. 10.0 ± 1.1%
20 µM. 22.0 ± 6.4%
200 µM. 57.8 ± 8.8%
Reductions in alkaline phosphatase mRNA levels mirrored Pb 2+ -induced inhibition of
enzyme activity.
Not applicable Guity et al. (2002)
Not applicable Schanne et al.
(1992)
Not applicable Angle et al. (1990)
Not applicable Klein and Wiren
(1993)