Fluoride Vol. 32 No. 4 243-247 1999 Research Report
243
ADVERSE EFFECTS OF COMBINED ARSENIC AND
FLUORIDE ON LIVER AND KIDNEY IN RATS
Kai-tai Liu,a Guo-Quan Wang, Li-Ying Ma,
Ping jang, Bi-Yu Xiao, Chen Zhang
Urumqi, Xinjiang, China
SUMMARY: In a subacute animal study, the effects of arsenic and fluoride on
liver and kidney in rats were investigated. The results indicated that arsenic,
fluoride and their combination affected the activities of superoxide dismutase
(SOD) and glutathione peroxidase (GSH-Px) and the contents of malondialdehyde (MDA) and sulphhydryl groups (-SH). Antagonistic effects were found
between arsenic and fluoride as well as on Zn, Fe, Ca, and Mg in liver and Ca,
Mg, Sr, and Al in kidney. Arsenic significantly increased the liver and kidney
content of Fe. For Mn there seemed to be synergism between arsenic and fluoride. The effects of arsenic and fluoride on liver and kidney have two aspects: one is direct action; the other is indirect – disturbances of free radical
balance and abnormal metabolism of some inorganic elements.
Keywords: Antioxidases, Arsenic-fluoride poisoning, Arsenism, Lipid peroxidation, Metallic elements, Rat liver, Rat kidney.
INTRODUCTION
Combined arsenic-fluoride poisoning is an exceptional disease in the
world. Since the 1960s, a large number of wells have been dug due to lack of
water in the Kuitun area of China. Unfortunately, this water is abundant in
fluoride as well as arsenic. After the 1970s, endemic fluorosis and arsenism
appeared among the residents in some parts of the area, involving about
50,000 people and an area of 1200 square kilometers. Both domestic and foreign scientific investigators have studied arsenism and fluorosis, and the results indicate that both arsenic and fluoride are able to cause injury to liver
and kidney.1-3 But studies of the combined effects of fluoride and arsenic on
liver and kidney, especially in low dose and long-term contact conditions have
not been reported. In recent years areas of arsenic-fluoride poisoning have
been successively discovered in the provinces of Neimeng and Gueizhou besides Xinjiang. It is therefore highly important to investigate the pattern and
mechanism of combined arsenic and fluoride injury on liver and kidney.
With the further investigation on the theory of free radicals, it has been
found that free radicals are new pathogenic factors which induce damage to
lipid peroxidation. Simultaneously they might be the original adverse reactions from toxicants. Under normal conditions, the level of free radical production and elimination keeps a dynamic balance, and the metabolism of metallic elements maintains the relative stability. In order to investigate the
effects of arsenic and fluoride together on lipid peroxidation and antioxidant
systems and the metabolism of metallic elements, the effects of arsenic and
fluoride on MDA, SOD, GSH-Px, -SH and nine metallic elements on liver and
kidney were studied by means of a subacute animal experiment.
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aFor correspondence: Department of Environmental Hygiene, Xinjiang Medical University, Urumqi, Xinjiang, China 830054.
244
Liu, Wang, Ma, Jang, Xiao, Zhang
MATERIALS AND METHODS
Fifty six healthy Wistar rats (NO.0000569) weighing 140-160 g at the beginning of the experiment were obtained from the Laboratory Animal Center
of Shanghai Medical University. The rats were randomly divided into four
equal groups of 14 animals each: F group, As group, F+As group, and the
control group. All rats were housed in the same room with free access to food
and water. The control group was given distilled water in which the fluoride
and arsenic concentration was 0 mg/L. The experimental groups were given
drinking water containing 150 mg/L sodium fluoride (NaF), 75 mg/L arsenic
trioxide (As2O3), and 150 mg/L NaF + 75 mg/L As2O3, respectively.
After six months the rats were killed. The hepatic and renal tissues (approximately 0.3 g each) were quickly removed, weighed, homogenized, and
centrifuged. The supernatant was then assayed for the activities of superoxide
dismutase (SOD), glutathione peroxidase (GSH-Px), and the contents of
malondialdehyde (MDA) and sulphhydryl groups (-SH).4-7 Other hepatic and
renal tissue were baked at 80°C, and then assayed with an “Inductively Coupled Plasma Atomic Emission Spectrometer” (ICP-AES) for metallic elements
(Cu, Zn, Fe, Cr, Pb, Sr, Al, Mg, and Ca).
Calculated values of experimental groups are reported as mean ± s.e. The
significance of the difference between means at the same period was determined by analysis of variance.
RESULTS
Hepatic tissue: Antioxdase levels (SOD, GSH-Px and -SH) decreased significantly by the sixth month in the groups of rats given water containing either
150 mg/L NaF or 75 mg/L As2O3. They also decreased in the 150 mg/L NaF
plus 75 mg/L As2O3 group, but were not significantly different from the controls (Table 1). The content of Zn, Fe, Ca, and Mg in the liver in the NaF
group and the As2O3 group were significantly different from the controls. The
content of Mg in the NaF + As2O3 group was lower than in the control group.
In this study, other elements were not significantly different among the four
groups (Tables 2 and 3).
Table 1. Hepatic tissue SOD, GSH-Px activities, and MDA, -SH concentrations
Group
Control
NaF
As2O3
NaF+As2O3
MDA
(nmol/mgpro)
7.40 ± 3.68
9.99 ± 2.37
6.47 ± 2.48
7.88 ± 3.08
SOD
(U/mgpro)
122.81 ± 26.32
98.25 ± 18.53ad
99.83 ± 7.56 ac
120.30 ± 17.56
GSH-Px
(U/mgpro)
386.40 ± 74.48
246.57 ± 39.46bd
241.12 ± 39.64bd
382.28 ± 65.49
-SH
(g/mgpro)
79.13 ± 13.64
48.25 ± 8.92ad
49.51 ± 6.27bd
66.96 ± 18.93
Note: Compared with Control group - a: P<0.05 b: P<0.01
Compared with NaF + As2O3 group - c: P<0.05 d: P<0.01
Renal tissue: Lipid peroxidation level increased in the As 2O3 group, but antioxidase levels were lower than in the control group (Table 4). The content of
Fluoride 32 (4) 1999
Adverse effects of arsenic and fluoride on liver and kidney in rats
245
Fe in the NaF + As 2O3 group was highest among all 4 groups, and Cr was
lowest in the NaF group (Table 5). The contents of Mg, Ca, Sr and Al in the
NaF and As2O3 groups were significantly lower than in the control and the
NaF + As2O3 groups (Table 6).
Table 2. Hepatic tissue Zn, Ca, Mg, and Fe concentrations (g/g)
Group
Control
NaF
As2O3
NaF+As2O3
Zn
280.43 ± 143.22
225.89 ± 81.43f
745.29 ± 278.06bd
247.01 ± 131.62
Ca
826.38 ± 207.91
519.13 ± 140.06bc
629.63 ± 140.02a
771.60 ± 149.97
Mg
Fe
521.25 ± 44.17
710.44 ± 300.85
394.17 ± 49.79bd 791.91 ± 255.32f
420.31 ± 40.76b 1315.47 ± 409.90bd
470.73 ± 53.99b 898.65 ± 280.68
Note: Compared with Control group - a: P<0.05 b: P<0.01
Compared with NaF + As2O3 group - c: P<0.05 d: P<0.01
Compared with As2O3 group - f: P<0.01
Table 3. Hepatic tissue Mn, Cu, Sr, Pb, and Cr concentrations (g/g)
Group
Mn
Cu
Sr
Control
2.06 ± 0.86 11.17 ± 5.51
0.80 ± 0.29
NaF
1.85 ± 0.24
9.01 ± 1.38
0.56 ± 0.08
As2O3
3.27 ± 1.83 11.40 ± 4.10
0.75 ± 0.31
NaF+As2O3
2.51 ± 2.11
9.20 ± 5.08
0.68 ± 0.14
Note: Comparison among the four groups P<0.05
Pb
5.99 ± 2.81
4.95 ± 2.25
7.05 ± 2.98
6.10 ± 2.31
Cr
7.49 ± 3.98
6.25 ± 2.05
10.11 ± 5.59
8.70 ± 3.71
Table 4. Renal tissue SOD, GSH-Px activities, and MDA, -SH concentrations
Group
Control
NaF
As2O3
NaF+As2O3
MDA
(nmol/mgpro)
3.16 ± 1.45
4.46 ± 1.32
5.11 ± 1.23a
4.24 ± 0.74
GSH-Px
(U/mgpro)
92.46 ± 26.47
58.76 ± 24.93b
41.79 ± 18.07b
50.54 ± 26.27b
-SH
(g/mgpro)
454.41 ± 92.16
327.32 ± 111.78ae
243.14 ± 54.95bd
399.37 ± 72.76
SOD
(U/mgpro)
68.82 ± 17.96
43.84 ± 8.33b
39.80 ± 9.05bc
51.56 ± 12.02b
Note: Compared with Control group - a: P<0.05 b: P<0.01
Compared with NaF + As2O3 group - c: P<0.05 d: P<0.01
Compared with As2O3 group - e: P<0.05
Table 5. Renal tissue Fe, Mn, Cr, Zn, and Pb concentrations (g/g)
Group
Fe
Control
623.97 ± 260.25
NaF
584.68 ± 280.83df
As2O3
917.52 ± 258.67b
NaF+As2O3 1056.25 ± 130.23b
Mn
Cr
Zn
1.25 ± 0.38 10.58 ± 5.35 372.96 ± 184.40
0.98 ± 0.24d 4.89 ± 2.57ade 404.75 ± 245.34
1.33 ± 0.61 10.97 ± 6.43 398.28 ± 163.71
2.42 ± 1.19be 14.32 ± 5.62 570.69 ± 203.42
Pb
10.66 ± 6.07
10.71 ± 3.93
14.99 ± 8.56
16.80 ± 9.12
Note: Compared with Control group - a: P<0.05 b: P<0.01
Compared with NaF + As2O3 group - c: P<0.05 d: P<0.01
Compared with As2O3 group - e: P<0.05 f: P<0.01
Fluoride 32 (4) 1999
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Liu, Wang, Ma, Jang, Xiao, Zhang
Table 6. Renal tissue Mg, Ca, Sr, and Al concentrations (g/g)
Group
Control
NaF
As2O3
NaF+As2O3
Mg
456.06 ± 80.60
338.46 ± 40.27bc
323.05 ± 48.08bc
414.12 ± 66.79
Ca
942.32 ± 184.38
650.38 ± 121.71bd
688.32 ± 66.04bd
954.55 ± 155.59
Sr
Al
1.13 ± 0.18
142.63 ± 47.95
0.91 ± 0.26bd 72.71 ± 20.87bd
0.87 ± 0.17bd 78.37 ± 24.55bd
1.22 ± 0.18
144.14 ± 54.18
Note: Compared with Control group - b: P<0.01
Compared with NaF + As2O3 group - c: P<0.05 d: P<0.01
DISCUSSION
Activities of many enzymes and the levels of inorganic elements are important factors for keeping in good health. When they become abnormal, the
structure and function of internal organs of the body can be disturbed. It has
been reported that fluoride and arsenic cause injury to liver and kidney.8-11 By
using the method of subacute animal experimentation, we have examined the
effects of arsenic, fluoride, and arsenic plus fluoride on liver and kidney of
rats. Our findings can be summarized as follows:
Effects on liver: Arsenic, fluoride, and their combination affected the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and
the contents of malondialdehyde (MDA) and sulphhydryl groups (-SH), and of
Zn, Fe, Ca and Mg. There were antagonistic effects on antioxidation between
arsenic and fluoride. Due to this antagonism between the effects of arsenic
plus fluoride, Ca and Mg in rat liver were lower than from the effects of either
one when used alone.
Effects on kidney: Arsenic increased the contents of malondialdehyde (MDA)
and caused accumulation of Fe. In its effect on Cr, arsenic reduced the action
of fluoride. Effects of the combination of arsenic and fluoride on SOD, GSHPx and -SH in rat kidney were greater than those of arsenic or fluoride alone.
The combined action of arsenic and fluoride increased the content of Mn. In
this respect, there was synergism between arsenic and fluoride.
As indicated above, the toxicity of arsenic and fluoride in liver and kidney
has two aspects. One is the direct action. The other is indirect action – the disturbance of free radical balance and abnormal metabolism of some inorganic
elements.
In view of the antagonism found in many indices in liver and kidney, cell
metabolism processes were affected. As a result, normal metabolism of cells
must have been disturbed with injury to liver and kidney.
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Published by the International Society for Fluoride Research
Editorial Office: 17 Pioneer Crescent, Dunedin 9001, New Zealand
Fluoride 32 (4) 1999