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Influence of potassium and sodium on uptake and retention of cesium-134 in rats
ARCHIVES
OF
BIOCHEMISTRY
Influence
AND
BIOPHYSICS
66, 177-182 (1957)
of Potassium and Sodium on Uptake and Retention of Cesium-134 in Rats’
F. R. Mraz, Marie LeNoir, J. J. Pinajian and H. Patrick From the University of Tenn.essee, Btomic Energy Commission Agricullural Research Program, Oak Ridge, Tennessee Received
May 3, 1956
Sodium and potassium are important minerals in metabolism, diffusion, and water and electrolyt,ic balance. Absorption of potassium by man is slower t,han sodium uptake. Exchange of intracellular and ext,racellular sodium is rapid, while that for pobassium is slower. Love and Burch (1) reported that potassium and cesium behaved similarly in the however, cesium exchanged at a slower rate. human erythrocytes; Hamilton (2) and Hood and Comar (3) reported a relatively large accumulation of cesium in the muscle tissue after dosing with cesium. Since cesium is one of the more import,ant fission products, information on factors controlling its biological behavior appears desirable. Its slow movement, biological similarity to potassium, and long half-life should make it an excellent tool to use in predicting how potassium behaves. EXPERIMENTAL A total of 110 weanling rats, uniform in size, were used during these studies. The potassium-deficient basal diet was similar bo the one used for rabbits by Hove and Herndon (1). It had the following percentage composition: casein 20, st.arch 64, cellulose 3, Wesson oil 4, vitamin concent,rnte 4 (which contained riboflavine, 1 This manuscript is published with the permission of the Director of the University of Tennessee Agricultural Experiment Station, Knoxville, Tennessee. The radioactive materials used in this work were obtained from the Oak Ridge National Laboratory on allocation from the U. S. Stomic Energy Commission. This work was completed under Contract No. AT-40.1-GEN-242 between the University of Tennessee, College of Agriculture, and the Atomic Energy Commission. 177
178
MRAZ,
LENOIR,
PINAJIAN
AND
PATRICK
TABLE I Cesium Content of Tissues and Ezcreta of Rats Fed Diets of Diffe’tent Potassium Content” Cages
Supplement
Femur
Blood
Liver
Muscle
Kidney
Spleen
-.__-
l-2
3-4 5-6 7-8
.-
Basal only 0.3% KC1 0.6’% KC1 0.9% KC1 L.S.D.b
0.93 0.56 0.56 0.57 --N.S.
Total fecal excretion -__
Total urinary excretion
%/g.
%/g.
%I&
%/rat
%/rot
0.131 0.073 0.063 0.049
1.54 0.74 0.73 0.75
2.46 1.68 1.67 1.79
2.96 1.49 1.22 1.25
1.45 0.72 0.84 0.87
3 28 35 47
0.003
0.32
N.S. ( 1.11 IO.53
0.68 0.88 1.76 1.54 -N.S.
13
Total excretion %hf
__ -
4 29 37 49 12
0 Expressed as per cent of administered dose. b L.S.D. = Least significant difference at the 5% level between means of treatments thiamine, pyridoxine, vitamin Brz , p-aminobenzoic acid, niacin, choline chloride, calcium pantothenate, inositol, vitamin A, and vitamin D2) and potassiumdeficient salt 5. The potassium-deficient salt was the one used by Hove and Herndon (4). When sodium was studied, this element was omitted from the basal diet. In all studies the rats were fed the basal diet for at least 7 days before receiving the supplemented experimental diets. Each rat received 5 microcuries (JJC.)of cesium-134 subcutaneously. The samples assayed for cesium-134 were wet-ashed with nitric acid, and activity was determined in a scintillation counter. The standard was made acid with hydrochloric acid, and cesium chloride was added. This is desirable since cesium-134 is essentially carrier-free. A total of four experiments were conducted. The influence of potassium intake on cesium retention and excretion was studied in Expt. 1. After receiving the potassium-deficient diet for 7 days, 20 rats were divided in four equal groups and given diets containing graduated amounts of potassium chloride as outlined in Table I. They were maintained on the supplemented diets for 7 days, placed in metabolism cages, and given the nuclide. Seventy-two-hour cesium-134 balance studies were made. The cesium-134 contents of the femur, blood, liver, muscle, kidney, and spleen were determined. The influence of dietary potassium on retention and excretion of cesium was determined in Expt. 2. As in the first experiment, the rats were fed the potassiumdeficient diet for 7 days. Twenty-four rats were then divided into four equal groups and placed in the metabolism units, and cesium-134 was administered. Twenty-four hours after receiving the nuclide, they were supplied with diets containing graduated amounts of potassium (Table II). This initial 24hr. period was thought to provide ample time for the nuclide to enter the tissues. Sevenday balance studies were made, and the tissues were assayed for cesium-134 as in Expt. 1.
CESIUM-1%
IN
TABLE
179
RATS
II
Cesiunt Content of Tissues and Excreta of Rats Fed Diets of Different Potassium Co&@
Cages
Blood
Supplement
Liver
Kidney
None 0.4yo KC1 0.8yo KC1 1.2yo KC1
Femur
Total Total GIlary fecal excreexcretion tion -
0.023 0.014 0.011 10.011 N.S.
%I&
%/ET.
%I femur
%/rat
%/rat
%/rat
0.35 0.28 0.25 0.26
0.89 0.48 0.44 0.44 .- --
0.35 0.28 0.23 0.23
1.17 0.92 0.85 0.84
0.23 0.18 0.18 0.17
19 30 34 37 __-_
0.39 0.53 0.70 0.70
19 31 35 38
0.10
0.06
0.19
0.05
5
0.15
4
0.04
-
TABLE
-
Supplement
l-2 3-4 5-6 7-8 9-10 11-12 13-14 ---
-
=
-
=
IFemur
Blood
%lg.
%I femur
%/g.
%h t
%/rotI:%/rot
1.84 1.58 0.93 1.22 1.10
4.28 3.75 1.37 3.78 1.82
1.70 2.10 1.32 2.30 1.24
1.22 1.15 0.89 0.97 0.75
0.075 0.075 0.039 0.070 0.050
0.4 0.7 5.3 1.0 12.0
0.63 0.60 2.18 0.71 2.12
1.0 1.3 7.5 1.7 14.1
1.62 1.71
0.69 0.70
1.38 1.58
1.00 0.81
0.37 0.53
0.044 0.043
5.1 11.3
1.81 1.75
6.9 13.1
1.55
0.66
1.39
0.84
N.S.
-N.S.
5.4
I iIUSClf
Liver
I Cidne]
Spk!eIl
%/g.
%/9.
%/g.
3.26 3.85 1.84 3.41 1.98
_-
e
.-
--
--
L.S.D.*
-
of Different Total I urinary excre~ tion
--
None 0.5yo NaCl 0.6% KC1 1 .O% NaCl 1 .2yo KC1 0.5yo NaCl 0.6% KC1 1 .O’% NaCl 1.2% KC1
means of treat-
III
Cesium Content of Tissues and Excreta of Rats Fed Diets Potassium and Sodium Content”
Cages
.
%/K.
a Expressed as per cent of administered dose. * L.S.D. = Least significant difference at the 5yo level between merits .
F
TOtal excretion
%/K.
-LSD.*
MuscIe
-__
I-
l-2 3-4 66 7-8
Spleen
--
-
a Expressed as per cent of administered * L.S.D. = Least significant difference ments.
-
-
dose. at 5yo level
between
_-
-_
0.48 -
-
5.7
means of treat-
180
MRAZ,
LENOIR,
PINAJIAN
TABLE
AND
PATRICK
IV
Cesinm Cont.ent of Tissues and Excreta of Rats Fed Diets of Dij’eerent Sodium Content” -
Supplement nhscie
Liver
T,“,‘,“: excretion
Femur
Total excretion
__%/P.
l-2 3-4 5-6 7-8 ---___-
9wrar %/rat
%/g.
None 0.5yo NaCl 1.0% NaCl 1 .5yo NaCl
1.31 1.13 1.09 1.0’9 ----
0.42 0.33 0.26 0.30
0.35 / 0.064 0.30 0.053 0.26 0.044 0.23 0.051 ---___
L.S.D.b
N.S.
N.S.
0.08
a Expressed as per cent of administered b L.S.D. = Least significant difference ments.
dose. at 1% level
0.010
between
47 59 60 66
0.96 1.07 0.87 1.02 __-
48 60 61 67
10
N.S.
9
means of treat-
Experiment 3 dealt with the influence of dietary potassium and sodium on cesium uptake and excretion. The basal diet was made deficient in both potassium and sodium and fed to 42 rats for 7 days before supplementation with potassium and sodium as indicated in Table III. After receiving the supplemented diets for 7 days, the seven groups of rats were placed in metabolism units and the nuclide was administered. Four-day balance studies were obtained. The tissues were studied as in the two previous experiments. The influence of dietary sodium on cesium retention and escretion was studied in Expt. 4. Twenty-four rats were placed on a sodium-deficient diet (containing 0.5% potassium chloride) for 7 days and then placed in metabolism cages, and cesium-134 was administered. Twenty-four hours later, they were divided into four groups of six rats each and given graduated amounts of sodium chloride (Table IV). Seven-day balance studies were made. The tissues were analyzed for cesium-134 as indicated in the previous experiments. RESULTS
The results of the first experiment are summarized in Table I. The differences in total excretion between rats fed a diet containing no potassium chloride and those fed diets supplemented with potassium chloride proved to be significant at the 5 % level of confidence. There was a trend toward greater excretion of the nuclide as more increments of potassium chloride were added, and the difference observed between rats fed the 0.3 or 0.6 % potassium chloride diets and those fed the 0.9 % potassium chloride diet was also found to be significant. The percentage excretion was greatest during the 24-hr. period following the adminis-
CESIUM-1%
IN
RATS
181
tration of the nuclide. Cesium retention in the tissues of rats fed diets supplemented with potassium chloride was significantly lower than those not supplemented. The degree of potassium chloride supplementation had no appreciable effect on retention of cesium-134 by the t,issues studied. The muscle and kidney tissues retained the great,est concentration of t,he nuclide, wit,h the liver and spleen next. The influence of dietary potassium on retention of body cesium was studied in Expt. 2 and is summarized in Table II. In this st’udy, t’he rats were depleted of potassium for 7 days, then given cesium-134 so that t,he body could distribute it before receiving graduated amounts of potassium. Total excretion of cesium-134 was found to be significantly greater in those groups supplemented with potassium chloride. The difference in total excretion between the rats fed diets supplemented with 0.8 or 1.2% potassium chloride and those fed the 0.4% potassium chloride diet also proved t’o be significant at the 5 % level of confidence. As in the first experiment, most of the cesium-134 was excreted in the urine. Significant differences in retent,ion by tissues were noted between the rats fed the unsupplemented diet and those fed diets supplement,ed with potassium chloride. The degree of potassium chloride supplementation had no appreciable effect on retention of cesium-134 by the t,issues studied. The cumulative excretion of cesium-134 over a 7-day period indicates t,hat once cesium becomes associated with a tissue, it probably is bound in a relatively stable complex and the excretion represents extracellular cesium and that which is freed during intracellular catabolism. The relation of dietary potassium and sodium to cesium retention and excretion was investigated in Expt. 3, and the results are summarized in Table III. It may be not,ed that the sodium chloride supplement,ation had only a slight influence on excretion of cesium-134 or on its removal from the tissues. The rats fed diets supplemented with potassium chloride excreted significantly more cesium-134 than did those rat’s receiving no potassium chloride supplementation. Urinary excretion of cesium-134 was significantly greater on the diets cont,aining 1.2% potassium chloride t,han on any other diets being fed. In most inst,ances, the rat’s fed t,he pot,assium chloride supplemented diets retained significantly less cesium-134 in their tissues than did those fed diets not supplemented with potassium chloride. The values indicated for urinary excretion of cesium-134 were lower than those in other experiments due to low urinary output and poor consumption of feed on diets low in sodium chloride.
182
MRAZ,
LENOIR,
PINAJIAN
AND
PATRICK
The last experiment, Table IV, was designed to show the influence of dietary sodium on excretion of body cesium. The rats were fed a sodiumdeficient diet for 7 days and then given cesium-134. Twenty-four hours after the rats received this nuclide, graduated amounts of sodium chloride were fed. A significant difference was observed in total excretion of the nuclide between the sodium chloride supplemented groups and that not supplemented. Increased sodium intake increased the excretion of the nuclide, but the rate of loss was not in proportion to sodium intake. Urine production in the groups receiving sodium chloride supplementation was greater than that of the deficient diet. No significant differences attributable to treatment were observed between the tissues. It would appear that sodium chloride influences extracellular cesium more than intracellular if one assumesthat the slow rate at which cesium leaves the muscle and kidney is due to its being bound within the cell and that additional increments of sodium chloride cannot exert their influence as a result. SUMMARY
The decrease in retention and increase in excretion of cesium when the dietary potassium is increased demonstrate that these two minerals might play a similar role. Dietary potassium increased the rate of excretion of body cesium. Cesium is ,probably present in bound forms in the soft tissues such as muscle and kidney and is freed chiefly after catabolism and not by ionic exchange. Sodium increases excretion of cesium when the diet is adequate in potassium. This increased excretion may involve extracellular more than intracellular cesium. REFERENCES 1. LOVE, W. D., AND BURCH, G. E., J. Lab. Clin. Med. 41, 351 (1953). 2. HAMILTON, J. G., MDDC 1160, Atomic Energy Commision, June 11, 1947. 3. HOOD, S. L., AND COMAR, C. L., Arch. Biochem. and Biophys. 46, 423 (1953). 4. HOVE, E. L., AND HERNDON, J. F., J. Nutrition 66, 363 (1955).
OF
BIOCHEMISTRY
Influence
AND
BIOPHYSICS
66, 177-182 (1957)
of Potassium and Sodium on Uptake and Retention of Cesium-134 in Rats’
F. R. Mraz, Marie LeNoir, J. J. Pinajian and H. Patrick From the University of Tenn.essee, Btomic Energy Commission Agricullural Research Program, Oak Ridge, Tennessee Received
May 3, 1956
Sodium and potassium are important minerals in metabolism, diffusion, and water and electrolyt,ic balance. Absorption of potassium by man is slower t,han sodium uptake. Exchange of intracellular and ext,racellular sodium is rapid, while that for pobassium is slower. Love and Burch (1) reported that potassium and cesium behaved similarly in the however, cesium exchanged at a slower rate. human erythrocytes; Hamilton (2) and Hood and Comar (3) reported a relatively large accumulation of cesium in the muscle tissue after dosing with cesium. Since cesium is one of the more import,ant fission products, information on factors controlling its biological behavior appears desirable. Its slow movement, biological similarity to potassium, and long half-life should make it an excellent tool to use in predicting how potassium behaves. EXPERIMENTAL A total of 110 weanling rats, uniform in size, were used during these studies. The potassium-deficient basal diet was similar bo the one used for rabbits by Hove and Herndon (1). It had the following percentage composition: casein 20, st.arch 64, cellulose 3, Wesson oil 4, vitamin concent,rnte 4 (which contained riboflavine, 1 This manuscript is published with the permission of the Director of the University of Tennessee Agricultural Experiment Station, Knoxville, Tennessee. The radioactive materials used in this work were obtained from the Oak Ridge National Laboratory on allocation from the U. S. Stomic Energy Commission. This work was completed under Contract No. AT-40.1-GEN-242 between the University of Tennessee, College of Agriculture, and the Atomic Energy Commission. 177
178
MRAZ,
LENOIR,
PINAJIAN
AND
PATRICK
TABLE I Cesium Content of Tissues and Ezcreta of Rats Fed Diets of Diffe’tent Potassium Content” Cages
Supplement
Femur
Blood
Liver
Muscle
Kidney
Spleen
-.__-
l-2
3-4 5-6 7-8
.-
Basal only 0.3% KC1 0.6’% KC1 0.9% KC1 L.S.D.b
0.93 0.56 0.56 0.57 --N.S.
Total fecal excretion -__
Total urinary excretion
%/g.
%/g.
%I&
%/rat
%/rot
0.131 0.073 0.063 0.049
1.54 0.74 0.73 0.75
2.46 1.68 1.67 1.79
2.96 1.49 1.22 1.25
1.45 0.72 0.84 0.87
3 28 35 47
0.003
0.32
N.S. ( 1.11 IO.53
0.68 0.88 1.76 1.54 -N.S.
13
Total excretion %hf
__ -
4 29 37 49 12
0 Expressed as per cent of administered dose. b L.S.D. = Least significant difference at the 5% level between means of treatments thiamine, pyridoxine, vitamin Brz , p-aminobenzoic acid, niacin, choline chloride, calcium pantothenate, inositol, vitamin A, and vitamin D2) and potassiumdeficient salt 5. The potassium-deficient salt was the one used by Hove and Herndon (4). When sodium was studied, this element was omitted from the basal diet. In all studies the rats were fed the basal diet for at least 7 days before receiving the supplemented experimental diets. Each rat received 5 microcuries (JJC.)of cesium-134 subcutaneously. The samples assayed for cesium-134 were wet-ashed with nitric acid, and activity was determined in a scintillation counter. The standard was made acid with hydrochloric acid, and cesium chloride was added. This is desirable since cesium-134 is essentially carrier-free. A total of four experiments were conducted. The influence of potassium intake on cesium retention and excretion was studied in Expt. 1. After receiving the potassium-deficient diet for 7 days, 20 rats were divided in four equal groups and given diets containing graduated amounts of potassium chloride as outlined in Table I. They were maintained on the supplemented diets for 7 days, placed in metabolism cages, and given the nuclide. Seventy-two-hour cesium-134 balance studies were made. The cesium-134 contents of the femur, blood, liver, muscle, kidney, and spleen were determined. The influence of dietary potassium on retention and excretion of cesium was determined in Expt. 2. As in the first experiment, the rats were fed the potassiumdeficient diet for 7 days. Twenty-four rats were then divided into four equal groups and placed in the metabolism units, and cesium-134 was administered. Twenty-four hours after receiving the nuclide, they were supplied with diets containing graduated amounts of potassium (Table II). This initial 24hr. period was thought to provide ample time for the nuclide to enter the tissues. Sevenday balance studies were made, and the tissues were assayed for cesium-134 as in Expt. 1.
CESIUM-1%
IN
TABLE
179
RATS
II
Cesiunt Content of Tissues and Excreta of Rats Fed Diets of Different Potassium Co&@
Cages
Blood
Supplement
Liver
Kidney
None 0.4yo KC1 0.8yo KC1 1.2yo KC1
Femur
Total Total GIlary fecal excreexcretion tion -
0.023 0.014 0.011 10.011 N.S.
%I&
%/ET.
%I femur
%/rat
%/rat
%/rat
0.35 0.28 0.25 0.26
0.89 0.48 0.44 0.44 .- --
0.35 0.28 0.23 0.23
1.17 0.92 0.85 0.84
0.23 0.18 0.18 0.17
19 30 34 37 __-_
0.39 0.53 0.70 0.70
19 31 35 38
0.10
0.06
0.19
0.05
5
0.15
4
0.04
-
TABLE
-
Supplement
l-2 3-4 5-6 7-8 9-10 11-12 13-14 ---
-
=
-
=
IFemur
Blood
%lg.
%I femur
%/g.
%h t
%/rotI:%/rot
1.84 1.58 0.93 1.22 1.10
4.28 3.75 1.37 3.78 1.82
1.70 2.10 1.32 2.30 1.24
1.22 1.15 0.89 0.97 0.75
0.075 0.075 0.039 0.070 0.050
0.4 0.7 5.3 1.0 12.0
0.63 0.60 2.18 0.71 2.12
1.0 1.3 7.5 1.7 14.1
1.62 1.71
0.69 0.70
1.38 1.58
1.00 0.81
0.37 0.53
0.044 0.043
5.1 11.3
1.81 1.75
6.9 13.1
1.55
0.66
1.39
0.84
N.S.
-N.S.
5.4
I iIUSClf
Liver
I Cidne]
Spk!eIl
%/g.
%/9.
%/g.
3.26 3.85 1.84 3.41 1.98
_-
e
.-
--
--
L.S.D.*
-
of Different Total I urinary excre~ tion
--
None 0.5yo NaCl 0.6% KC1 1 .O% NaCl 1 .2yo KC1 0.5yo NaCl 0.6% KC1 1 .O’% NaCl 1.2% KC1
means of treat-
III
Cesium Content of Tissues and Excreta of Rats Fed Diets Potassium and Sodium Content”
Cages
.
%/K.
a Expressed as per cent of administered dose. * L.S.D. = Least significant difference at the 5yo level between merits .
F
TOtal excretion
%/K.
-LSD.*
MuscIe
-__
I-
l-2 3-4 66 7-8
Spleen
--
-
a Expressed as per cent of administered * L.S.D. = Least significant difference ments.
-
-
dose. at 5yo level
between
_-
-_
0.48 -
-
5.7
means of treat-
180
MRAZ,
LENOIR,
PINAJIAN
TABLE
AND
PATRICK
IV
Cesinm Cont.ent of Tissues and Excreta of Rats Fed Diets of Dij’eerent Sodium Content” -
Supplement nhscie
Liver
T,“,‘,“: excretion
Femur
Total excretion
__%/P.
l-2 3-4 5-6 7-8 ---___-
9wrar %/rat
%/g.
None 0.5yo NaCl 1.0% NaCl 1 .5yo NaCl
1.31 1.13 1.09 1.0’9 ----
0.42 0.33 0.26 0.30
0.35 / 0.064 0.30 0.053 0.26 0.044 0.23 0.051 ---___
L.S.D.b
N.S.
N.S.
0.08
a Expressed as per cent of administered b L.S.D. = Least significant difference ments.
dose. at 1% level
0.010
between
47 59 60 66
0.96 1.07 0.87 1.02 __-
48 60 61 67
10
N.S.
9
means of treat-
Experiment 3 dealt with the influence of dietary potassium and sodium on cesium uptake and excretion. The basal diet was made deficient in both potassium and sodium and fed to 42 rats for 7 days before supplementation with potassium and sodium as indicated in Table III. After receiving the supplemented diets for 7 days, the seven groups of rats were placed in metabolism units and the nuclide was administered. Four-day balance studies were obtained. The tissues were studied as in the two previous experiments. The influence of dietary sodium on cesium retention and escretion was studied in Expt. 4. Twenty-four rats were placed on a sodium-deficient diet (containing 0.5% potassium chloride) for 7 days and then placed in metabolism cages, and cesium-134 was administered. Twenty-four hours later, they were divided into four groups of six rats each and given graduated amounts of sodium chloride (Table IV). Seven-day balance studies were made. The tissues were analyzed for cesium-134 as indicated in the previous experiments. RESULTS
The results of the first experiment are summarized in Table I. The differences in total excretion between rats fed a diet containing no potassium chloride and those fed diets supplemented with potassium chloride proved to be significant at the 5 % level of confidence. There was a trend toward greater excretion of the nuclide as more increments of potassium chloride were added, and the difference observed between rats fed the 0.3 or 0.6 % potassium chloride diets and those fed the 0.9 % potassium chloride diet was also found to be significant. The percentage excretion was greatest during the 24-hr. period following the adminis-
CESIUM-1%
IN
RATS
181
tration of the nuclide. Cesium retention in the tissues of rats fed diets supplemented with potassium chloride was significantly lower than those not supplemented. The degree of potassium chloride supplementation had no appreciable effect on retention of cesium-134 by the t,issues studied. The muscle and kidney tissues retained the great,est concentration of t,he nuclide, wit,h the liver and spleen next. The influence of dietary potassium on retention of body cesium was studied in Expt. 2 and is summarized in Table II. In this st’udy, t’he rats were depleted of potassium for 7 days, then given cesium-134 so that t,he body could distribute it before receiving graduated amounts of potassium. Total excretion of cesium-134 was found to be significantly greater in those groups supplemented with potassium chloride. The difference in total excretion between the rats fed diets supplemented with 0.8 or 1.2% potassium chloride and those fed the 0.4% potassium chloride diet also proved t’o be significant at the 5 % level of confidence. As in the first experiment, most of the cesium-134 was excreted in the urine. Significant differences in retent,ion by tissues were noted between the rats fed the unsupplemented diet and those fed diets supplement,ed with potassium chloride. The degree of potassium chloride supplementation had no appreciable effect on retention of cesium-134 by the t,issues studied. The cumulative excretion of cesium-134 over a 7-day period indicates t,hat once cesium becomes associated with a tissue, it probably is bound in a relatively stable complex and the excretion represents extracellular cesium and that which is freed during intracellular catabolism. The relation of dietary potassium and sodium to cesium retention and excretion was investigated in Expt. 3, and the results are summarized in Table III. It may be not,ed that the sodium chloride supplement,ation had only a slight influence on excretion of cesium-134 or on its removal from the tissues. The rats fed diets supplemented with potassium chloride excreted significantly more cesium-134 than did those rat’s receiving no potassium chloride supplementation. Urinary excretion of cesium-134 was significantly greater on the diets cont,aining 1.2% potassium chloride t,han on any other diets being fed. In most inst,ances, the rat’s fed t,he pot,assium chloride supplemented diets retained significantly less cesium-134 in their tissues than did those fed diets not supplemented with potassium chloride. The values indicated for urinary excretion of cesium-134 were lower than those in other experiments due to low urinary output and poor consumption of feed on diets low in sodium chloride.
182
MRAZ,
LENOIR,
PINAJIAN
AND
PATRICK
The last experiment, Table IV, was designed to show the influence of dietary sodium on excretion of body cesium. The rats were fed a sodiumdeficient diet for 7 days and then given cesium-134. Twenty-four hours after the rats received this nuclide, graduated amounts of sodium chloride were fed. A significant difference was observed in total excretion of the nuclide between the sodium chloride supplemented groups and that not supplemented. Increased sodium intake increased the excretion of the nuclide, but the rate of loss was not in proportion to sodium intake. Urine production in the groups receiving sodium chloride supplementation was greater than that of the deficient diet. No significant differences attributable to treatment were observed between the tissues. It would appear that sodium chloride influences extracellular cesium more than intracellular if one assumesthat the slow rate at which cesium leaves the muscle and kidney is due to its being bound within the cell and that additional increments of sodium chloride cannot exert their influence as a result. SUMMARY
The decrease in retention and increase in excretion of cesium when the dietary potassium is increased demonstrate that these two minerals might play a similar role. Dietary potassium increased the rate of excretion of body cesium. Cesium is ,probably present in bound forms in the soft tissues such as muscle and kidney and is freed chiefly after catabolism and not by ionic exchange. Sodium increases excretion of cesium when the diet is adequate in potassium. This increased excretion may involve extracellular more than intracellular cesium. REFERENCES 1. LOVE, W. D., AND BURCH, G. E., J. Lab. Clin. Med. 41, 351 (1953). 2. HAMILTON, J. G., MDDC 1160, Atomic Energy Commision, June 11, 1947. 3. HOOD, S. L., AND COMAR, C. L., Arch. Biochem. and Biophys. 46, 423 (1953). 4. HOVE, E. L., AND HERNDON, J. F., J. Nutrition 66, 363 (1955).