Chung K, Romero N, Tinker D, Keen C L, Amemiya K, Rucker R
Department of Nutrition, University of California, Davis 95616.
J Nutr. 1988 Jul;118(7):859-64. doi: 10.1093/jn/118.7.859.
Weanling male Sprague-Dawley rats were fed one of four diets that varied in Cu, Zn or Cd content. To the control diet (I) Cu, Zn and Cd were added at 10, 100 and 0 mg/kg diet, respectively. Diets II and III also contained 10 mg/kg of dietary Cu, except that Zn was elevated to 1000 mg/kg for diet II, or Cd was added at 10 mg/kg for diet III. Diet IV was deficient in Cu (less than 1 mg/kg) with Zn at 100 mg/kg and no added Cd. At wk 6 postweaning, half of the rats fed diets I and IV were injected once with Cd acetate (5 mg Cd/kg body weight). The immediate response to Cd injection was an increase in metallothionein accumulation (three- to fourfold) and in Cu,Zn superoxide dismutase (SOD) accumulation (1.2- to 1.5-fold) in liver. SOD was estimated in an ELISA. These responses were not influenced by a change in Cu status (I vs. IV). However, in functional assays, SOD enzymatic activity was about half that of the control values. In this regard, SOD appears to be given high priority with respect to the utilization of cellular Cu, i.e., a 10-fold reduction in hepatic Cu only resulted in a twofold reduction in SOD activity and the amount of apoenzyme remained at normal levels.
将断乳的雄性斯普拉格-道利大鼠喂以四种铜、锌或镉含量不同的日粮之一。对照日粮（I）中分别添加10、100和0毫克/千克日粮的铜、锌和镉。日粮II和III也含有10毫克/千克日粮的铜，只是日粮II中锌含量提高到1000毫克/千克，或者日粮III中添加10毫克/千克的镉。日粮IV缺铜（低于1毫克/千克），含100毫克/千克锌且未添加镉。在断奶后第6周，给喂食日粮I和IV的大鼠中的一半注射一次醋酸镉（5毫克镉/千克体重）。注射镉后的即时反应是肝脏中金属硫蛋白积累增加（三到四倍）以及铜锌超氧化物歧化酶（SOD）积累增加（1.2到1.5倍）。通过酶联免疫吸附测定法评估SOD。这些反应不受铜状态变化（I与IV）的影响。然而，在功能测定中，SOD酶活性约为对照值的一半。在这方面，就细胞铜的利用而言，SOD似乎被给予了高度优先地位，即肝脏铜含量降低10倍仅导致SOD活性降低两倍，且脱辅基酶的量保持在正常水平。
