@Copyright 1985 by The Humana Press Inc. All rights of any nature whatsoever reserved.

0163-4984/85/0811-0263504.00

Interactions Between Selenium and Tin, Selenium and Lead, and Their Effects on ALAD Activity in Blood Mo CHIBA,* N. FUJIMOTO, N. OYAMADA, AND Mo KIKUCHI

Department of Hygiene, Juntendo University School of Medicine Hongo 2-I-1, Bunlq/o-ku, Tot9/o 113, Japan Received May 28, 1985; Accepted June 20, 1985 ABSTRACT Interactions of tin and selenium, as well as of lead and selenium, were investigated in male ICR mice. The toxic effects of selenium on mortality and body weight loss were reduced by simultaneous injection with tin or lead; among mice that were injected ip with selenium at 100 ~mol/kg, the 24 h survival rate was 20%, whereas among mice that were administered selenium and tin or selenium and lead at the dose of 100 ~mol/kg each, the rates were 100% and 90%, respectively. As for 8-aminolevulinic acid dehydratase (ALAD, EC 4.2.1.24), lead and tin were strong inhibitors, which is well known; selenium showed no effect. When more than an equimolar dose of sodium selenite was injected ip simultaneously with stannous chloride, the ALAD activity was completely retained. On the other hand, in the simultaneous injection with sodium selenite and lead acetate of differing ratios (Se/Pb), 1, 2.5, 5, and 7.5, selenium did not exhibit an obvious protective effect against the inhibition of ALAD activity caused by lead. It is suggested that selenium protects essential thiol groups in ALAD that are otherwise blocked by invading tin; in contrast, selenium, under similar conditions, does not prevent interactions of lead with enzyme thiol groups. I n d e x Entries; ~-Aminolevulinic acid dehydratase; tin; lead; selenium; toxic effects of selenium on body weight; selenium and tin, interactions between; selenium and lead, interactions between; ALAD activity in blood; toxic effects of selenium on mortality; sodium sele-

*Author to whom all correspondence and reprint requests should be addressed. Biological Trace Element Research

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voi. s, I 985

264

C h i b a et al. nite and stannous chloride, effect on ALAD activity; s o d i u m selenite and lead acetate, effect on ALAD activity; thiol groups, in ALAD; tin, inhibition on ALAD activity.

INTRODUCTION It is well k n o w n that lead, even at low dosages, inhibits the activity of erythrocyte 5-aminolevulinic acid dehydratase (ALAD, 5-aminolevulinate hydrolyase, EC 4.2.1.24), which is the second e n z y m e in porphyrin synthesis. ALAD is k n o w n to be a zinc-containing sulfhydryl enzyme. It was reported that the treatment of blood samples from lead-exposed h u m a n subjects or experimental animals, such as rabbits, mice, and rats, with glutathione (1,2), dithiothreitol (DTT) (3,4), zinc (5,6), zinc and DTT (4), a n d zinc and glutathione at 50~ (8), or heating at 60~ for 5 min (9), restored the activity of ALAD to normal. According to these results, it seems that lead inhibits ALAD activity, though this is not an irreversible effect. It was reported that bivalent tin inhibits erythrocyte ALAD activity in vivo (10) and both bivalent and tetravalent tin do so in vitro (11). The mechanism of this inhibition has not been elucidated. On the other hand, tl~e inhibitory mechanism of ALAD activity by lead has been studied in purified ALAD from bovine liver by Tsukamoko et al. (7). According to these authors, ALAD contains one zinc atom and eight sulfhydryl groups/subunit. The e n z y m e activity was completely lost, with a concomitant loss of b o u n d zinc, u p o n oxidation of the sulfhydryl groups to a disulfide or by mercaptide formation on reaction with lead. To study the m e c h a n i s m of tin inhibition of ALAD activity, four kinds of ALAD activity in each blood sample were assayed, (a) an original activity, i.e., the activity in the normal untreated blood, (b) DTT-modified activity, i.e., reactivated by DTT in vitro, (c) Zn-modified activity, i.e., reactivated by zinc in vitro, and (d) Zn-DTT-modified activity, i.e., reactivated by both zinc and DTT in vitro. Since selenium is k n o w n to interact with some heavy metals, we decided to study the combined effects of selenium and lead and of selenium and tin on survival rate and body wt in mice and on erythrocyte ALAD activity in vivo.

MATERIALS AND METHODS Animals Four-week old male ICR mice were purchased (Nippon Bio-Supp. Center Co. Ltd., Tokyo, Japan) and used after a 1-wk acclimatization period in a climatic chamber maintained at 25 + 1~ and 60 +- 5% relative humidity. During the acclimatizing period, 30 mice were h o u s e d in a Biological Trace Element Research

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Interactions Between Se and Sn or Pb

26.5

large aluminum cage; after treatment, small aluminum cages were used for housing five mice/cage. They were given a commercial solid diet (CE-2, Clea Japan Inc., Tokyo, Japan) and distilled water ad Iibitum.

Treatment Lead, tin, and selenium compounds used were lead acetate [Pb(CH3COO)2.3H20], stannous chloride (SnC12-2H20), and sodium selenite (Na2SeO3). Each compound was dissolved in 5% glucose solution immediately before use. In the experiments involving simultaneous injections of two elements, the lead or tin solution was injected into the left peritoneal cavity and the selenium solution into either the right peritoneal cavity or the dorsal subcutis. A s s a y o f A L A D Activity in Blood Blood was collected, under light ether anesthesia, from the femoral vein 18-20 h after administration of lead or tin. Heparin was used as an anticoagulant agent. Whole blood was diluted with 9 vol demineralized water and used for the enzyme solution. ALAD activities measured in each blood sample were (a) the original activity, (b) DTT-modified activity, (c) Zn-modified activity, and (d) Zn-DTT-modified activity. Four substrate solutions were prepared: (a) Contained 25 mM ~-aminolevutinic acid (ALA) in0~ sodium phosphate buffer (pH 6.8); (b) contained, in addition to substrate solution (a), 50 mM DTT; (c) used 1.0 mM zinc instead of DTT in substrate solution (b); and (d) consisted of 25 mM ALA, 50 mM DTT, 1.0 mM zinc, and 0.25M sodium phosphate buffer (pH 6.8). The incubtion mixture contained 5 mM ALA, 10 mM DTT, 0.2 mM zinc, and 50 mM sodium phosphate buffer. Incubation was performed at 37~ for 30 rain. The reaction was terminated by addition of 0.5 mL 1M trichloroacetic acid containing 70 mM mercuric chloride. Porphobilinogen (PBG) formed during incubation was determined after developing the color with Ehrlich reagent (2 g p-dimethylaminobenzaldehyde, 67 mL acetic acid, 31 mL 70% perchloric acid, and 2 mL concentrated hydrochloric acid). ALAD activity was represented as a unit (~mol PBG/mL erythrocytes/h, at 37~ that was calculated from absorbance at 555 nm, a molar extinction coefficient of 6.2 x 10 4, and its hemotocrit value.

Determination of Lead in Blood Lead in blood was determined by the direct method with a flameless atomic absorption spectrophotometer (AAS), according to the method, of Fernandez (12). The blood sample was diluted 10- to 20-fold with 0.1% Triton X-100 solution. Each 20 p~L was applied to AAS (Perkin-Elmer model 603 equipped with HGA 2200 controller, MA, USA) through an auto sampler (Perkin-Elmer model AS-l, MA, USA). Background was corrected by deuterium lampo Biological Trace Element Research

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Chiba et al.

Determination of Tin in Blood Simple wet-ashing technique was applied prior to the determination of tin by AAS. Two milliliters nitric acid and 0.5 mL perchloric acid were added to 0.2 mL whole blood sample. Glass sample tubes were kept at 130-140~ for 1 h, then the temperature was increased to 200~ and maintained for 1-2 h. This heating process was carried out by using a hot block bath (model TPB-32, Toyo Seisakusho Co., Tokyo, Japan) set in a draftchamber. To the cooled samples were added, in the following order, 1 mL of N hydrochloric acid, 2 mL 10% ascorbic acid, 3 mL concentrated hydrochloric acid, and 2 mL methylisobutylketone saturated with demineralized water. Sample tubes were vigorously shaken for 5 min by a shaker (Type MS-l, Sugiyamagen Environmental Science Co., Ltd., Tokyo, Japan). Each 20qxL of organic-solvent layer was transferred to AAS, which was described above in the Determination of Lead section. The detailed conditions for AAS employed in the procedure were described in a previous paper (13).

Determination of Selenium in Blood Selenium was determined by the method of Oyamada and Ishizaki

(14). Approximately, 0.1 mL blood was put into a combusting crucible (Uniseal 23 mL, Amco, Tokyo, Japan) with lmL 5N nitric acid. The crucible was kept in a muffle furnace (model MFP-300N, Ikeda-Rika Co., Tokyo, Japan) at 200~ for 8 h. After cooling by water, the ashed contents and 4N hydrochloric acid, which was used for rinsing the inside of the crucible, were pooled and adjusted to 4N hydrochloric acid. Two mililiters of 20% hydroxylamine was added to the ashed solution and boiled for 10 min on a hot plate (model EH 102, Hitachi Co., Tokyo, Japan). After transferring the solution into a separating funnel, the sample was shaken with 0.02% dithizone-CC14 solution for 5 min and the organic-solvent layer transferred to AAS (model 170-50 equipped with a model HFA heated-graphite atomizer and a deuterium background corrector, Hitachi Co., Tokyo, Japan). All glassware for element determination was immersed in 30% nitric acid for 2 d and thoroughly rinsed with demineralized water. All chemical reagents used for this purpose were either analytical or super special grade.

RESULTS MoRality and Body Weight The mortality was observed for 35 d in the following groups; control, a single dose of selenite (10, 50, 75, or 100 Ixmol/kg), a single dose of S n 2+ (10, 50, or 100 ~xmol/kg), a single dose of Pb 2+ (10, 50, or 100 ixmol/kg), simultaneous administration of Sn 2+ and selenite (Sn, 10 ixmol/kg; Se, 1, Biological Trace Element Research

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10, 25, 50, or 75 ~mol/kg, as well as equimolar dosage of 10, 50, 75, or 100 ~mol/kg each), and simultaneous administration of Pb 2+ and selenite (equimolar dosage of 10, 50, or 100 ~mol/kg each). The mortality figure represents the % survival of animals in each group (see Fig. 1). The groups in which all experimental mice remained alive were omitted from Fig. 1. The weight gain in each group is s h o w n in Fig. 2. This gain is expressed as % average body weight of the individual group on the respective observation days vs that at the beginning of the experiment. The growth rate was almost the same as the control in all groups administered with a single dose of Sn 2+ or Pb 2+, the group with a single dose of selenite 10 ~mol/kg, the four groups with S n 2+ and selenite (Sn 10 + Se 1; Sn 10 + Se 10; Sn 10 + Se 25; and Sn 50 + Se 50 ~mol/kg), and the group with Pb 2+ 10 ~mol/kg and selenite 10 ~mol/kg. In the groups receiving a single dose of selenite 50, 75, or 100 ~mol/kg, the survival rate and the body weight loss were the worst, that is, growth retardation was observed within 1 d after administration in these groups; 80 and 90% of the animals died within 1 and 6 d, respectively, in the group administered 100 ~mol/kg (in which only one mouse survived and gained weight after 2 wk of administration). Even though mice were injected with selenite 100 ~mol/kg, as long as an equimolar injection of S n 2+ o r P b 2 + followed, the mortality reduced markedly, but growth retardation was not improved. W h e n both selenite and S n 2+ o r selenite and P b 2 + w e r e injected at the dose of 50 ~mol/kg each, no mouse died during the experimental period; loss of body weight was observed only during the initial 3 d, then turned to weight gain. C o n s u m e d food and drinking water were m e a s u r e d in each cage, and the average food weight and water vol c o n s u m e d / m o u s e was calculated. At the beginning of this study, mice were 5 w k old, and average food and water intakes were 5.3 -+ 0.29 g (mean + SD, n = 13 cages) and 7.55 + 1.62 mL (n = 11 cages) a mouse/d, respectively. Intake a m o u n t s of food and drinking water w e r e parallel to the change of body weight. Although the least intake of food and water was 0.3 g and 1.4 mL, respectively, in the group receiving selenite 100 ~mol/kg, w h e n the equimolar Pb 2+ o r Sn 2+ was accompanied with selenite, these intake amounts increased to 4.3 g and 5.6 mL, respectively. A L A D A c t i v i t y in B l o o d Single Dose of S n 2 +, Selenite, or P b 2 +

ALAD activities in all Figs. are expressed as % values as compared with the control group by using average activity in each group. As s h o w n in Fig. 3(a), S n 2 + inactivated ALAD activity in blood, d e p e n d i n g on the dose, whereas selenite, ran~ing from 1 to 75 ~mol/kg, p r o d u c e d no significant change. As for Pb L+, only one dosage, 10 ~mol/kg, was employed here because m a n y reports on this kind of study have been deBiological Trace Element Research

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268

Chiba et aL Se alone 1 0 0 ~ ....................... 5oi

............. :.~~ 5

m~!_!.~g. ........ ::: ........... :...: ............... : .........

10

15

20

25

30

35

:6

2'5

do

3'5

:6

d5

3b

:6

2~

~o

Se+Pb IOOjjrno|/kcj each 100 ~ - ~

"~

5o

,b

?5

Se75 pmol/kg +Sn 10 p mol/kg 100

~

50

,b

,~ ....

Se+Sn 75pmol/kg each

-~,1~176 I 5

,o

,'5

d5

Se.t-Sn lOOpmol/kg each

Z

~oof

I

t~

"~ 50

"3's Days after injection

Fig. 1o Survival rates of mice injected with tin and/or selenium or lead and/or selenium. Each group consists of 5 or 10 mice.

Biological Trace E]ement Research

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Interactions Between Se and Sn or Pb --

269

( 1 0 p r n o l / k g ) acKi various dosage of Se

Control 140 t20

a ........

= ,oo

140

5

,o

,~

2o

2~

3b

ds

z=

120

100

Se alone

k.... 9

.-'-qfdl"

80

.....................(ioo>

5 >, '~ I00 r

10

15

20

25

30

35

An equ~rno~ d~sage of S~ and Se 140

5

10

1:5

20

25

30

35

~ 120

.....~_

tOOl....m .

,oo ~

80

,

;

10

.

.

.

.

.

.

.

.

.

.

.

--,a,.; .................

,5

20

L

......

I

J

25

30

3;

....~ - "

5

10

An equimolat of dosage of Pb and Se 15

20

25

30

35

140

5o1 Pb a~on~

hoo_L_-.ti)

...a-----"

~o~ 120

140

T~

0 100

"~ t20

80. 100

5

10

15

20

2'5

Days after injection 10 Days

15 after

20

25

30

35

injection

Fig~ 2. Changes in the body wt of mice treated with tin and/or selenium or lead and/or selenium. Each group consists of 5 or 10 mice. The numerals in parenthesis represent administered dosages in Dmol/kg~

scribed elsewhere (1,15). DTT-, Zn-, and Zn-DTT-modified activities of ALAD in blood are shown in Fig. 3(b), (c), and (d), respectively. Decreased ALAD activity caused by Sn 2+ was restored almost completely by treatment with DTT [Fig. 3(b)] or DTT and zinc [Fig. 3(d)] and insufficiently by treatment with zinc alone [Fig. 3(c)]. On the other hand, decreased ALAD activity caused by Pb 2 + was restored almost completely by treatment with zinc alone and with DTT and zinc [Figs. 3(c), (d)] and

Biological Trace Element Research

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270

Chiba et aL ALAD

~,e,m~wm ( },JrltoD kq ) rl (a) Conlfot 5

Se 10

3

25

6

50 75

5

activity 50

(,,) 1OO

I

l

I

J

5

Pb 10 (b) Control

5

Sn 10

4

25 50

5

75

3

3

tOO

3

Se 10

3

50

5

75

5 3

Pb 10 (c) Control Sn 10 25 50 75 100 Se 10 50 75 Pb 10

J i---

C-

I

j

5 __

~ ~

t f

s5 3

]

(d} Control 5 Sn tO

4

25

3

50

5

75 100 SelO

3

25

6

50

5

75

5

Pb 10

3

3 ....... 3

I I I I

i

I I

f

Fig. 3. ALAD activity in blood from mice ip injected with tin, lead, or selenium: (a) the original activity; (b) the DTT-activating activity; (c) the Znactivating activity; (d) the Zn.DTT-activating activity.

insufficiently by DTT alone [Fig. 3(b)], Selenite has no effect on the A L A D activities determined by the four different kinds of treatments. Element concentrations in blood are s h o w n in Table I. N o tin was detected unless tin was injected.

Biological Trace Element Research

Vol. 8, 1985

,m Po

Ix0

oa

r3

2.07 • 1.50 (n = t0)

Pb f o u n d ttg/dg blood

51.95 • 16.85 (n = 8)

10

10 42.39 • 6.35 07 = 8)

Pb (btmol/kg) i n j e c t e d

37.90 +- 4.63 (n = 8)

1

68.50 • 24.36 (,7 = 5)

M e a n SD

50

78.22 _+ 11.53 (n = 9)

25

M e a n SD

75

M e a n SD

100

185.4 ~ 18 (n = 5)

50

328.78 + 30.53 (n = 4)

75

82.18 • 27.84 122.71 • 50.59 (,1 = 3) (n = 3)

Se (b~mol/kg) i n j e c t e d

38.48 • 6.99 (n = 3)

M e a n SD

M e a n SD 26.60 _+ 4.03 (t7 = 4)

25

10

"Blood was collected 18-20 h after ip injection. ~'ND: not detected. 'Mixed blood from five mice was used.

27.09 + 12.19 (n = 21)

ND b

Sn f o u n d , txg/dL b l o o d

Se f o u n d , ~g/dL blood

Cont.

Group

Sn ( ~ m o l / k g ) i n j e c t e d

TABLE 1 Tin, S e l e n i u m , a n d L e a d C o n c e n t r a t i o n s in B l o o d of M i c e A d m i n i s t e r e d T h o s e E l e m e n t s ~

272

Chiba et aL

Simultaneous Injection with Sn 2+ and Selenite or Pb 2+ and Selenite

W h e n mice were simultaneously administered with Sn 2+ and selenite at the dose of 10 ~mol/kg each, no inhibition of ALAD activity appeared [Fig. 4(a)]. No difference was found between injection of selenite into the peritoneal cavity and the subcutis. The ALAD activity did not decrease in the group receiving a mixture of S n 2 + and selenite immedi-

(a)

Treatment Se Sn Pb n -

ALAD

activity `50

/) 100

-

ip s(2 ip ip

ip

sc

ip ip

ip

ip 3

sc

ip 6

s (b) ip

-

-

I

5 3 7

sc ip

3

ip

ip

3

sc

ip

8

I

I

6 ip 3

ip sc -N(c)-

ip ip ~x= -

3 6 `5 3 7

ip sc

ip ip ip

3 3 8

-~

-~

6 ip 3

ip

ip 3

sc

ip 6

-

-

I I

I

`5

ip

3

sc ip

7 3

ip

ip

3

sc

ip

8

~

]

-- `5

ip sc

(d)-

I I

I

6 ip .3. ip 6

I I

I

ip 3

i# sc

I

I

I

I

I I

Fig. 4. ALAD activity in blood from mice simultaneously injected with tin and selenium or lead and selenium at the dose of 10 ~.mol/kg each: (a)-(d) are the same as those given in Fig. 4. *Mixed solution of 10 p~mol/kg each was injected ip. Biological Trace Element Research

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Interactions Between Se and Sn or Pb

ately after mixing both solutions. In the experiments of simultaneous injection with Pb 2+ and selenite, however, selenite did not prevent the inactivation of ALAD caused by Pb 2+ [Fig. 4(a)]. W h e n mice were injected with a mixed solution of Pb 2+ and selenite, ALAD activity decreased less than w h e n Pb 2§ was injected alone. Activity was higher in the group treated with DTT and Zn than in the groups treated with DTT and Zn alone and was comparable to that of the control group. Activity Treatment (,umol/kg} Se Sn Pb n o 0 10 8 1 10 10 10 25 10 50 10 o 10 10 50 10 75 10 3

(b) o 0 10 50 75 0 10 50 75

o

(c) O 0 0 10 10 10 25 10 50 10 0 10 50 75 (d)O 0 1 10 50 0

o

10 10 10 10

0

ALAD

a c t i v i t y (O/o) 50 100

I

I

I

5 8 3 5 4

10 10 10 10

3 5 5 3

0

5 3 3 5 4 3 5 5 3

10 10 10 10 0

10 10 10

1 I I

I

I

I

I 1 I I

I

I

t

5 8 8 3

10

10

10 10 10

75

10

I , ,

I

I

Fig. 5. ALAD activity in blood from mice simultaneously injected with tin 10 ~mol/kg and various dosages of selenium or lead 10 p.mol/kg and various dosages of selenium: (a)-(d) are the same as those given in Fig. 4. Biological Trace E]ement Research

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C h i b a et aL

in the g r o u p t r e a t e d with Pb 2 + alone was h i g h e r t h a n that in the g r o u p s treated w i t h Pb 2+ a n d selenite a n d lower t h a n the g r o u p t r e a t e d w i t h t h e mixed solution. A d m i n i s t e r e d R a t i o o f S e l e n i t e v s S n 2 + a n d S e l e n i t e vs P b 2 +

The a d m i n i s t e r e d d o s a g e of Sn 2+ was fixed at 10 ~mol/kg, a n d the s i m u l t a n e o u s injection d o s a g e of selenite was altered from 1, 10, 25, to 50 Izmol/kg. T h e results are s h o w n in Fig. 5. W h e n this ratio (Se/Sn) was larger t h a n 1, A L A D activity r e m a i n e d at a similar r a n g e to the controls. W h e n this ratio w a s 0.1, A L A D activity r e d u c e d m a r k e d l y . It w a s ass u m e d that a s e l e n i u m d o s e of m o r e t h a n an e q u i m o l a r d o s e of tin was n e e d e d to p r e v e n t the inactivation of A L A D activity c a u s e d by Sn 2+ . Administration w i t h an e q u i m o l a r of Sn 2+ a n d selenite, r a n g i n g f r o m 10, 25, 50 to 75 ~mol/kg, was tested. As s h o w n in Fig. 6, A L A D activity f r o m all Treatment

( p moll kg ) Se

Sn

n

(a) 0 0

0 10

5 8

10 25 50

10 25 50

3 6 5

75

75

5

0

0

5

0

10

8

10

10

3

50

50

5

75

75

5

0

0

5

0

10

3

10

10

3

50 75

50 75

5 5

(d) 0

0

5

0

10

8

10

10

3

25

25

6

50

50

5

75

75

5

(b)

(el

ALAD

activity

(O/o)

5O

100

1

1 1 I I I 1 I

I I I

i I

J

Fig. 6. ALAD activity in blood from mice simultaneously injected with equimolar tin and selenium: (a)-(d) are the same as those given in Fig. 4. Biological Trace Element Research

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Interactions Between Se and Sn or Pb

c o m b i n a t i o n s of Sn 2+ a n d selenite w a s c o m p a r a b l e to controls. DTTm o d i f i e d a n d Z n - D T T m o d i f i e d A L A D activities w e r e almost the same; slightly higher t h a n t h o s e of control in all g r o u p s except for a g r o u p injected w i t h Sn 2+ alone, w h i c h w a s m u c h h i g h e r in D T T - m o d i f i e d a n d Z n . D T T - m o d i f i e d activity than in the n o n m o d i f i e d activity. O n the o t h e r h a n d , in the g r o u p w i t h s i m u l t a n e o u s injections of Pb 2+ a n d selenite, no o b v i o u s p r e v e n t i v e effect u p o n the inhibitory effect of Pb 2 + o n A L A D activity w a s o b s e r v e d in a d o s a g e of 10 ~xmol/kg each, as s h o w n in Fig. 4. Therefore, a d m i n i s t r a t i o n with high d o s a g e s of selenite, 50 a n d 75 ixmol/kg, w a s tested. As s h o w n in Fig. 5, no r e m a r k a b l e i m p r o v e m e n t in A L A D activity w a s o b s e r v e d . W h e n selenite 75 }xmol/kg a n d Pb 2+ 10 ixmol/kg w a s a d m i n i s t e r e d , the n o n m o d i f i e d A L A D activity w a s a b o u t twice that of w h e n Pb 2 + w a s injected alone. In the g r o u p injected w i t h selenite 100 txmol/kg a n d Pb 2+ 10 jxmol/kg, all mice d i e d within 1 d. D T T - m o d i f i e d activity w a s i n c o m pletely r e s t o r e d , a n d that in the g r o u p injected w i t h l o w e r d o s a g e s of selenite w a s relatively h i g h e r than that in the g r o u p with h i g h e r d o s a g e s . N o r e s t o r a t i o n of Z n - m o d i f i e d A L A D activity w a s f o u n d . In this case, Z n - D T T - m o d i f i e d activity w a s also a l m o s t c o m p l e t e l y restored. Tin, lead, a n d s e l e n i u m c o n c e n t r a t i o n s of b l o o d in the a b o v e experim e n t s are s u m m a r i z e d in Tables 2(a), (b), a n d (c). F r o m the a b o v e results, it a p p e a r s that s e l e n i u m interacts with tin m o r e strongly t h a n w i t h lead.

TABLE 2(a) Selenium, Lead, and Tin Concentrations in Blood from Mice Administered Selenium and Tin or Selenium and Lead at the Dose of 10 }xmol/kg each Concentration in blood, txg/dL

Treatment, 10 fxmol/kg Se

Sn

Pb

Mean

--

21.92 42.39 35.50 22.15 29.04 35.46 33.25 39.55 34.59 38.20 36.16

ip SC

ip ip sc a

ip SC a

Selenium

ip ip ip a

ip ip ,7

SD + +_ _ _+ + +_ _+ + -+ + +

3.81 6.35 4.23 3.69 5.06 6.55 5.63 9.45 9.53 7.41 11.52

Tin (n) Mean

SD

(9) ND (8) (8) (8) (8) 18.64 _+ 6.07 (8) Trace (8) 14.10 +4.57 (9) ND (8) (8) (8)

Lead (n) Mean

SD

(n)

1.50

(10)

51.95 2 16.85

(8)

53.58 - 15.51 67.73 _+ 5.49 35.25 _+ 14.78

(8) (8) (8)

2.07 _

(7) (6)

'q'he mixture was administered ip. Biological Trace Element Research

VoL 8, I985

Chiba et aL

276 TABLE 2(b) Selenium and Tin Concentration in Blood of Mice Administered with Selenium and Tin Concentration in blood, p~g/dL

Treatment, ~mol/kg Se

Sn

0

0 25

25 25

50 50 75 75 10 25 50

25 50 50 75 75 10 10 10

Selenium Mean

SD

29.56 35.07 78.22 51.27

• 2.43 • 2.15 • 11.53 • 7.01 32.2" 185.4,, 114.9" 29.68 • 5.00 328.78 • 30.53 234.40 • 38.70 43.3 • 6.63 73.53 • 5.80 201.8"

Tin SD

(n) Mean

(7) ND (9) 34.17 • 7.43 (9) (9) ND (5) 69.19' (5) (5) ND (5) 82.18 • 27.84 (4) (5) 2.86 • 0.68 (8) 22.43 • 5.32 (4) ND (5) D

(n) (9)

(5)

(3) (3) (8)

"Mixed blood from five mice was used.

TABLE 2(c) Selenium and Lead Concentrations in Blood of Mice Administered Selenium and Lead Concentration in blood, #g/dL

Treatment, p,mol/kg

Selenium

Se

Pb

Mean

0 0 10 50 75

0 10 10 10 10

23.88 25.60 37.66 236.93 407.40

SD + • • • •

3.24 4.01 4.30 32.64 56.60

Tin (n) Mean (4) (4) (3) (3) (5)

2.23 42.79 33.62 30.68 30.18

• • • • •

SD

(11)

1.44 5.45 7.65 1.71 3.45

(5) (4) (3) (3) (5)

D T T and Zinc Dependency in Blood from/Vlice Administered with Sn 2§ and~or Selenite D T T a n d z i n c d e p e n d e n c y w a s o b s e r v e d in b l o o d a f f e c t e d b y Sn 2+ a l o n e at d o s e s of 10 a n d 50 i.tmol/kg, selenite a l o n e at 50 Dmol/kg, t h e c o m b i n a t i o n of Sn 2+ at 10 ~ m o l / k g a n d selenite at 50 Dmol/kg, a n d t h e c o m b i n a t i o n of Sn 2+ at 50 ~ m o l / k g a n d setenite at 50 Dmol/kg. E a c h b l o o d s a m p l e w a s collected 18 h after a d m i n i s t r a t i o n . T h e r e s u l t s are s h o w n in Fig. 7. DTT c o n c e n t r a t i o n in t h e i n c u b a t i o n m i x t u r e w a s n o t Biological Trace Element Research

VoL 8, 1985

277

Interactions Between S e and Sn or Pb (a)

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