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TIME
IN OAYS
Fig. 32.—The Ba plasma specific activity and the whole-bodyretention of this isotope in four beagles plotted as a func
of time after intravenous injection.
are both shown in graphical form in Figure 32. The
3113-day 1°°Ba retention point for Dog A22B was ob-
tained from radiochemical analysis of the entire skeleton.
The values listed in Table 8 and plotted in Figure
32 are expressed as percent of injected dose per gram
of skeletal calcium. It has been assumed that the
total skeletal calcium in Dogs 576 and A22B was 1.5%
of their respective total body weights: 150 ¢ calcium
for Dog 576 and 105¢ calcium for Dog A22B. The
total skeletal calelum in Dogs A22C and A22D was
measured. The values of the total skeletal calcium in
these two dogs were 91.5¢ for Dog A22C and 96.7 ¢
for Dog A22D. These stable calcium determinations on
both plasma and the complete skeletons were made on
a Perkin-Elmer atomic absorption spectrophotometer
by the method described in their handbook.“
Seven days before sacrifice (3106 days after the
183Ba injection) Dog A22B, at age 9.2 years, was injected with 2081 »Ci.of high specific activity “Ca as
part of a kinetic study.?”) At about the same time, its
two littermates were also injected intravenously with
tracers: Dog A22C received 300 Ci 18°Ba and Dog
A22D received both 423 «Ci of ®Ca and 315 .4Ci of
133Ba. The dogs were maintained in separate activity
cages for one week, during which time periodic blood
samples and daily fecal and urine samples were col-
lected. Data from the analysis of these specimens per-
mitted us to compare *®Ca and 18Ba retention
blood curves of Dog A22B at 8 months of age vs.
years of age. All four of the above mentioned cu:
are plotted on log-log scale in Figure 33.
Plasma Clearance
Three-milliliter samples
of heparinized
(0.02
0.05 ml of heparin) whole blood from Dogs A22B
0376 were sealed in glass vials and counted in a Nal{
well counter. The ®*Ba standard vial was counte:
the same manner. The concentration determinati
of '8Ba for the last four observations were made 11
pooled samples of plasma. The plasma was collec
over periods of about three months by taking appr:
mately 150 mi of whole blood from the appropriate «
every two weeks, separating the plasma, and sto:
it until a sufficient quantity had been obtained
gamma-ray analysis. The final collected volumes w
wet ashed with 2N HCl and concentrated down
3-ml volumes, which were sealed in glass vials
comparison with earlier samples. At sacrifice a ten
nal blood sample of 300 ml was taken from Dog 6
The observed values are listed in Table 9 as perc
of injected dose per milligram of calcium and plot:
in Figure 32 as percent injected dose per gram calci:
The Ba content in the blood plasma from Di
A22C and A22D was measured using liquid scintil
tion techniques. Aliquots of plasma separated fr:
a
ie