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RISS 인기검색어
- 검색키워드
- 저자 : ( David Ringer ) (검색결과 4 건)
- 무료
- 기관 내 무료
- 유료
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Influence of Dietary Zinc, Copper and Cadmium Levels on Rat Liver Aryl Sulfotransferase Ⅳ Activity
Keun Hee Chung,David P. Ringer,Kyung Ok Shin 한국영양학회 2006 Nutritional Sciences Vol.9 No.1
Aryl sulfotransferase (AST) Ⅳ is a liver enzyme involved in detoxication and has been shown to be susceptible to down regulation by a number of hepatotoxic xenobiotics. Studies presented here to investigate the ability of biological and non-biological divalent metal cations on AST Ⅳ activity showed that AST Ⅳ was strongly inhibited following in vitro or in vivo exposure to. Zn (Ⅱ), Co (Ⅱ) or Cd (Ⅱ). It was found that 0.025~2.5 ㎛ of these metal ions were sufficient to cause 50% of inhibition in vitro in purified AST Ⅳ and 0.25~25 ㎛ of these metal ions in liver cytosolic fractions. For the in vivo study, 1,000 ㎎ Cu (Ⅱ)/㎏, 2,000 ㎎ Zn (Ⅱ)/㎏ or 250 ㎎ Cd (Ⅱ)/㎏ was added to individual diets and administered to three (3) groups of rats over a 7 week period The Cu (Ⅱ)-supplemented diet produced no apparent change in rat growth rote and resulted in 30-fold increase in liver cytotolic Cu (Ⅱ) levels, suggesting that elevated levels of Cu (Ⅱ) ion in the liver were responsible for the loss of AST Ⅳ activity. In contrast, the Zn (Ⅱ)-supplemented diet caused a decrease in rot growth rates and resulted in zero increase in liver Zn (Ⅱ) levels, which suggested an indirect inhibition mechanism was caused by Zn (Ⅱ) in the liver. Rats were fed the Cd-supplemented diet also displayed a decrease in growth rote with little or no change in liver Cu (Ⅱ) or Zn (Ⅱ) levels. When the liver cytosols of rots from the metal ion diets were immunochemically analyzed for the AST Ⅳ and albumin contents, no significant changes were observed in albumin levels. However, AST Ⅳ contents in the cytosols of mts fed the Zn (Ⅱ)-supplemented diets showed a slight decrease in amount. These results showed that AST Ⅳ activity in vitro and in vivo can be inhibited by Cu (Ⅱ), Zn (Ⅱ), and Cd (Ⅱ) by apparently different mechanisms. The immediate response to a Zn injection showed a decrease in AST Ⅳ activity but not in the AST Ⅳ content in liver cytosol. These mechanisms appeared to involve direct actions of the metal ion on AST Ⅳ activity and indirect actions affecting AST Ⅳ amount.
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Keun Hee Chung,David P. Ringer,Kyung Ok Shin 한국영양학회 2006 Nutritional Sciences Vol.9 No.1
Purified rat liver aryl sulfotransferase Ⅳ (AST Ⅳ) was found to be inhibited in vitro by zinc, copper, cadmium and terbium, Among these four elements, zinc, copper and cadmium were all strongly inhibitory to the AST Ⅳ activity at very low concentratiom (2.5 ㎛ to 0.025 ㎛). In rat liver cytosol, zinc, copper and cadmium at 25 ㎛ to 0.025 ㎛ also decreased the AST Ⅳ activity to 50% of the controls. In order to assess the possible effects of these metals on the AST Ⅳ activity recovery pattern in vivo, studies on the relationship between these minerals and dietary 2-acetylaminofluorene were conducted Total of forty rats were fed one of five diets for 6 weeks: diet 1, Control diet phis 2-acetlyaminofluorene (0.05%); diet 2, zinc-deficient diet plus 2-acetlyaminofluorene; diet 3, zinc-supplement diet plus 2-acetylaminofluorene; diet 4, copper-supplement diet plus 2-acetiyaminofluorene; diet 5, cadmium-supplement diet plus 2-acetylaminofluorene. Half of the rats from each diet were changed to individual diet after 3 weeks of 2-acetylamnofluorene feeding. Placement of rats on the control diet following one cycle of 2-acetylaminofluorene feeding of 3 weeks without 2-acetylaminofluorene resulted in nearly full recovery of AST Ⅳ activity within 3 or 4 weeks. However, the rats fed diets that supplemented with zinc, copper or cadmium without 2-acetylaminofluorene showed a new pattern of lowered AST Ⅳ activity as early as the first cycle. Also, lowering in cytosolic AST Ⅳ contents was appeared in the Iivers from the rats, following one cycle of 2-acetlyaminofluorene feeding of 3 weeks, fed one of the diets that supplemented with copper, cadmium or zinc without 2-acetylaminofluorene for ensuing 3 weeks.
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