NERC-LV-539-32
THE BEHAVIOR OF 131I IN AN ARTIFICIAL RUMEN AND IN
THE SIMULATED FLUIDS OF THE ABOMASUM AND INTESTINE
Earl L. Whittaker
Delbtirt S, Bart*
National Environmental Research Center-Las Vegas
U. S. ENVIRONMENTAL PROTECTION AGENCY
Lis. ¥gs9 NV 89114
Published May 1974
This research performed under a Memorandum
of Understanding No. AT(26-l}-539
for the
U. S. ATOMIC ENERGY COMMISSION
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Protection Agency over similar ones not mentioned.
Available from the National Technical Information Service,
U. S. Department of Commerce,
Springfield, VA 22151
Price: paper copy $4.00, microfiche $1.45
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NERC-LV-539-32
THE BEHAVIOR OF 131I IN AN ARTIFICIAL RUMEN AND IN
THE SIMULATED FLUIDS OF THE ABOMASUM AND INTESTINE
by
Julius Barth
Earl L. Whittaker
Delbert S. Barth
National Environmental Research Center-Las Vegas
U. S. ENVIRONMENTAL PROTECTION AGENCY
Las Vegas, NV 89114
Published May 1974
This research performed under a Memorandum
of Understanding No. AT(26-l)-539
for the
U. S. ATOMIC ENERGY COMMISSION
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ABSTRACT
131
The in vitro conversion of I-labeled sodium iodide to volatile iodine
was investigated in the artificial rumen and in simulated abomasal and
101
intestinal fluids. In addition, the association of I-labeled iodide
with rumen juice sediment, which includes microflora and feed debris, was
also studied. The results show that under the conditions reported here,
101 1 01
I is not volatile. As much as three percent of the I was shown to
be associated with rumen juice sediment in the artificial rumen. This
value was reduced to 0.52 percent and 0.038 percent in the simulated
abomasal and intestinal fluids, respectively.
11
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ACKNOWLEDGMENTS
The authors thank J. A. Reagan for statistical analyses of the data
and G. D. Potter and W. W. Sutton for their helpful suggestions in
the preparation of this manuscript.
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INTRODUCTION
Gases of the rumen may be expelled by eructation and subsequently absorbed
by the lungs. At this laboratory it was observed that I appears in the
blood and milk of cattle very soon after an oral administration of I
iodide. It was therefore postulated that I could have been converted to
volatile iodine in the rumen and transported into the respiratory system by
eructation where it could be absorbed. Experiments using the artificial
rumen were designed to test this hypothesis.
Dougherty et aj_. (1965), discussing work of others concerning eructated rumen
gas, stated the following: A repetition by Dougherty ejt al_. (1962) of an
experiment performed many years ago by Dougherty (1940) very effectively
demonstrated that components of rumen gas which reach the lungs are
absorbed. Dougherty ejb al_. (1962) and Shipe et^ a\_. (1962) demonstrated
that certain odors carried in eructated gases from the rumen to the lungs
were absorbed, thereby contaminating the mammary blood supply and trans-
mitting off-flavors to the milk. The same substances tested in these
experiments were also absorbed by the portal blood; however, contamination
of milk was much slower by this route than it was when eructated gases
were allowed to enter the lungs.
131
This study was designed to assess the possibility that I iodide might
be converted to volatile iodine or methyl iodide in rumen juice which
could then be eructated into the respiratory tract. If iodide were indeed
1
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converted to iodine in the gastrointestinal tract, it would then be
necessary to account for I losses by eructation as well as recycling
of I via the respiratory system. Volatilization of I iodide from
simulated abomasal and intestinal juice was included in this study. In
131
addition, the binding of I to rumen microflora and other sediment was
also studied.
Barth and Bruckner (1969 a,b) effectively employed an artificial rumen
followed by simulated abomasal and intestinal fluids to study the uptake
by binding agents of Cs, strontium, and other essential cations in order
to reduce radionuclide transport to milk. This procedure also provides
a means for investigating the solubility or availability for absorption
of fallout radionuclides in a natural medium, taken directly from a
rumen-fistulated steer, in the presence of viable rumen microflora.
METHODS AND MATERIALS
The artificial rumen and simulated abomasal and intestinal fluid procedure
used is similar to that employed by Barth and Bruckner (1969 a,b) and is
briefly described here with necessary modifications. Each digestion flask
was prepared by addition of 250 ml of rumen juice to 250 ml of basal
medium in a one-liter Ehrlenmeyer flask containing 3.75 g of powdered
cellulose. The C02 outlet from each Ehrlenmeyer flask was connected
to an I scrubber consisting of a 1.5- by 20-cm column of activated
charcoal. The content of each flask was adjusted to pH 6.5 with saturated
sodium carbonate solution and dosed with 0.7 to 1.2 yCi of carrier-free
131
Na I. Digestion flasks were incubated for about 21 hours in a water bath
at 39°C, with a continuous stream of COp passing through the contents of each
flask.
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The artificial rumen fluid in each flask was then converted to simulated
abomasal fluid by addition of 125 ml of simulated abomasal juice contain-
ing 0.25 g pepsin and by adjusting the pH to three with 5.0 N HC1. The
resulting mixture was incubated for three hours. The C02 flow was allowed
131
to continue slowly in order to sweep gaseous I that might be produced
to the charcoal scrubber.
Following the abomasal digestion phase, the simulated abomasal fluid was
converted to a simulated intestinal fluid. One-hundred milliliters of
0.1N NaHC03 was added followed by 40 ml of bile. Fifty milliliters of
an enzyme preparation containing 6.0 g pancreatin, 0.3 g trypsin, and 0.3
g erepsin was added and the pH was adjusted to six with 5.0 N NaOH. In-
cubation continued for an additional three hours with a slow rate of (XL
flow.
At the beginning and end of each digestive phase, a 5-ml sample of rumen
juice was removed and pipetted directly into 50 ml of 0.1N NaOH for
131
radioanalysis of I. Upon completion of each digestive phase, an ad-
ditional 10-ml sample from each flask was removed and centrifuged for 20
minutes at the maximum speed of a Sen/all Table Model Centrifuge, Type M
(over 5000 rpm). The supernatant was decanted into 0.1N NaOH for radio-
analysis while the sediment was washed twice by resuspension in 5 ml of
water and recentrifuged. All supernatants were combined. The washed
sediment was analyzed for radioiodine. Fresh charcoal scrubbers were
131
used during each digestive phase for collection of gaseous I. Gamma
spectrometry was carried out using opposed 5- by 9-inch sodium iodide
crystals associated with a TMC 400-Channel Analyzer. Digestion flasks
were run in duplicate for three separate trials.
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A preliminary experiment was designed so that gas chromatography could
be used to determine the chemical form of any volatile iodine. This
operation was similar to the procedure described above except that the
C02 outlet was connected to a small filter flask which served as a trap.
This was followed by passing the gas through a 1.5- by 20-cm column of
a mixture of calcium chloride pellets and anhydrous calcium sulfate
which served as a drying agent. Plastic tubing was used to connect
this column to the first scrubber which consisted of a "U" tube containing
4 ml of toluene. The toluene scrubber was placed in a Dewar flask contain-
ing a slurry of ground dry ice and isopropyl alcohol. This was subsequently
attached to a column of activated charcoal which served as a backup scrubber.
Toluene was used only during the artificial rumen phase, while the charcoal
scrubber was used during all digestion phases.
During the preliminary trial only, one digestion flask was used. Rumen
juice was sampled at the beginning of the phase and at one, six, and
16-1/2 hours after dosing. Samples were collected at the beginning and
131
end of the abomasal and intestinal phases. The collection of I by
the toluene liquid scrubber permitted later separation of organic and
131
inorganic gaseous I by gas-liquid chromatography and possible
identification of organic and other forms.
RESULTS AND DISCUSSION
Results of the preliminary trial (data not shown) indicate practically no
loss of I from the digestive juices during the incubation periods.
1 "31
Virtually no I was recovered in the toluene and charcoal scrubbers or
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in the plastic tubing used. Chromatographic analysis, originally
scheduled on the toluene to determine the form of I present, was
not necessary since the toluene contained no radioactivity.
The averages of the results of the three in vitro trials are shown in
Table I. An analysis of variance indicates that there was no significant
difference (p »0.05) between the activity levels in any of the nine
fluids sampled. This indicates little, if any, loss due to volatility
of I or binding of I to sediment.
Radioactivity associated with the sediment was not significantly above
background. Therefore, although some activity is associated with the
sediment, it is within the limits that might be expected from experimental
error. There was a sharp drop in sediment-associated I following
abomasal digestion and almost no I was associated with sediment during
the intestinal phase. This may be due to enzymatic digestion of the
rumen microflora and other sediment present.
I 01
Absence of I deposited on the charcoal scrubbers also demonstrates
little or no I volatility in these digestive fluids. Though not
statistically significant (p »0.05), there appears to be a slight drop
in I remaining in whole juice and supernatant between the beginning
and the end of the abomasal phase. This cannot be accounted for by
I association with sediment or deposition on the charcoal scrubbers
131
and is possibly due to binding of I to the container during incuba-
tion or centrifugation.
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131
TABLE I
I DISTRIBUTION DURING IN VITRO DIGESTION
Whole juice start
Percent of I remaining
Artificial
Rumen %
100.00
102.36*
Abomasal
Phase %
100.00
96.52
Intestinal
Phase %
100.00
98.59
at end of phase
101
Percent of I in supernatant
at end of phase
131
Percent of I in sediment
at end of phase
Percent of I deposited
on charcoal during phase
98.16
3.13
94.53
0.521
99.82
0.038
0.00062 0.001038 0.0000
*Value greater than 100$ is due to counting error.
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1 "31
These results suggest that I iodide present in rumen contents is
not volatilized and it is not likely that it would be eructated as
gaseous iodine into the bovine respiratory system where it might be
absorbed through the tissues of the respiratory tract.
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REFERENCES
1. Barth, J., Bruckner, B. H., Evaluation of Clays as Binding Agents for
Reduction of Radionuclides in Milk. Binding Properties of Natural and
Hydrogen Form Clays with Strontium and Essential Cations in Artificial
Rumen and in Simulated Abomasal and Intestinal Fluids. J. Agr. Food
Chem. 17:1340-1343, I969a.
2. Barth, J., Bruckner, B. H., Evaluation of Clays as Binding Agents for
Reduction of Radionuclides in Milk. Binding Properties of Clays with
134cs in Artificial Rumen and in Simulated Abomasal and Intestinal
Fluids, and Uptake of '34cs by Rumen Microflora. J. Aqr. Food Chem.
17:1344-1346, 1969b.
3. Dougherty, R. W., Physiological Studies of Induced and Natural Bloat
in Dairy Cattle. J. Am. Vet. Med. Assoc. 96_:43-46, 1940.
4. Dougherty, R. W., Mullenax, C. H, Allison, M. J., Physiological
Phenomena Associated with Eructation in Ruminants, in Dougherty, R. W.,
Allen, R. S., Burroughs, W., Jacobson, N. L., McGilliard, A. D.,
Physiology of Digestion in the Ruminant, pp. 159-170, Butterworth,
Washington, 1965T
5. Dougherty, R. W., Shipe, W. F., Gudnason, G. V., Ledford, R. A.,
Peterson, R. D. Scarpellino, R., Physiological Mechanisms Involved
in Transmitting Flavors and Odor to Milk. I. Contribution of
Eructated Gases to Milk Flavor. J. Dairy Sci. _45:472-476, 1962.
6. Dougherty, R. W., Stewart, W. E., Nold, M. M., Lindahl, I. L.,
Mullenax, C. H., Leek, B. F., Pulmonary Absorption of Eructated
Gas in Ruminants. Am. J. Vet. Res. _23:205-212, 1962.
7. Shipe, W. F., Ledford, R. A., Peterson, R. D., Scanlan, R. A.,
Geerken, H. F., Dougherty, R. W., Morgan, M. E., Physiological
Mechanisms Involved in Transmitting Flavors and Odors to Milk.
II. Transmission of Some Flavor Components of Silage. J. Dairy Scj.
45:477-480, 1962.
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