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

AX5-129
Table AX5-8.3. Bone Cell Cultures Utilized to Test Effects of Lead
Compound
Dose/Concentration
Duration Exposure
Route Species Effects Blood Level Reference
Stable “Pb”
5 mg/mL in drinking
water given during
gestation.
On GD 18, 50 µCi
210 Pb given i.v. to
pregnant dams
210 Pb nitrate
6.5 to 65 µM
5 min to 2 h
In medium
210 Pb nitrate
5 µM
20 hours
In medium
Pb acetate
0 to 50 µM
20 h
In medium
Rat
(fetal bone
organ culture)
Mice
(bone cell
isolation from
calvaria)
Mice
(osteoclastic
bone cell
isolation from
calvaria)
Mice
(osteoclastic
bone cell
isolation from
calvaria)
PTH (3885 IU/mg bone) enhanced cell-mediated release of 210 Pb from bone. Release
of 210 Pb was accompanied by proportional loss of stable Pb and calcium from treated
bones.
Time: Release of 210 Pb (EM/CM ratio)
0 min 1.00
10 min 0.82 ± 0.05
2 hr 1.12 ± 0.04
6 hr 1.59 ± 0.08*
24 hr 3.69 ± 0.15*
48 hr 3.75 ± 0.09*
48 hr 0.78 ± 0.14* (in presence of 30 mU/mL salmon calcitonin)
*Different from 1.00, p < 0.01.
Uptake of 210 Pb by OC cells rapid.
OC cells have greater avidity for Pb compared to OB cells.
OC cell uptake of Pb almost linear vs. little increase in Pb uptake by OB cells with
increasing Pb concentrations in media.
15–30% release of 210 Pb label occurred in OC cells over 2 h time period.
Physiological concentrations of PTH resulted in marked increase in 210 Pb and 45 Ca
uptake by OC cells. 210 Pb uptake linear over PTH concentrations of 50 to 250 ng/mL).
Media concentrations of Pb $26 µM enhanced calcium uptake by cells.
Three readily exchangeable kinetic pools of intracellular Pb identified, with the
majority (~78%) associated with the mitochondrial complex.
Cultures were labeled with 45 Ca (25 µCi/mL) for 2 or 24 h and kinetic parameters
were examined by analysis of 45 Ca washout curves.
In kinetic analysis using dual-label (1–2 µCi/mL 210 Pb and 25 µCi/mL 45 Ca) wash out
curves, the Ca:Pb ratios of the rate constants were ~1:1, suggesting similar cellular
metabolism.
Not given/not
applicable
Rosen and Wexler
(1977)
Not applicable Rosen (1983)
Not applicable Pounds and Rosen
(1986)
Not applicable Rosen and Pounds
(1988)