亚硒酸钠与细胞的作用

通过测定巨噬细胞的存活率、脂质过氧化、细胞内游离Ｃａ２＋、Ｍｇ２＋的浓度和红细胞膜Ｃａ２＋－ＡＴＰ酶和Ｍｇ２＋－ＡＴＰ酶的活性，研究了亚硒酸钠与细胞的作用。结果表明高浓度的Ｎａ２ＳｅＯ３（≥１０－４ｍｏｌ·Ｌ－１）有明显的细胞毒性；Ｎａ２ＳｅＯ３对巨噬细胞的毒性作用引起细胞内游离Ｃａ２＋、Ｍｇ２＋浓度升高；但Ｍｇ２＋浓度升高比Ｃａ２＋慢；较高浓度的Ｎａ２ＳｅＯ３（≥１０－５ｍｏｌ·Ｌ－１）能抑制红细胞膜Ｃａ２＋－ＡＴＰ酶和Ｍｇ２＋－ＡＴＰ酶的活性，但对Ｍｇ２＋－ＡＴＰ酶活性的抑制作用要低于对Ｃａ２＋－ＡＴＰ酶活性的抑制作用。     

丁烯酸内酯对心肌细胞Ca^2＋通道的阻滞作用

采用贴附式膜片钳技术，在培养的Ｗｉｓｔａｒ大鼠单个心肌细胞上记录丁烯酸内酯对Ｂ，Ｌ，Ｔ３型Ｃａ２＋通道单通道电活动的影响。结果表明，丁烯酸内酯浓度为３００ｍｇ·Ｌ－１时，心肌细胞Ｂ，Ｌ，Ｔ３型Ｃａ２＋通道均受到明显的阻滞，其阻滞作用表现在使Ｂ，Ｌ，Ｔ３型Ｃａ２＋通道的开放时间分别缩短４６６％，５０５％和１５３％，关闭时间分别延长３０５％，３２２％和３２８％，使通道的开放概率分别下降５６８％，６１５％和３５０％。而对流过Ｂ，Ｌ，Ｔ３型Ｃａ２＋通道的Ｂａ２＋流幅值均无明显影响。     

硒代蛋氨酸与亚硒酸钠对心肌细胞动作电位影响的比较

在培养的Ｗｉｓｔａｒ大鼠乳鼠心肌细胞上观察了硒代蛋氨酸与亚硒酸钠对膜电位活动的影响。结果表明，硒代蛋氨酸与亚硒酸钠（１．０，２．０，４．０ｍｇ／Ｌ）均可使心肌细胞动作电位幅值（ＡＰＡ）、超射（ＯＳ）、阈电位（ＴＰ）、最大舒张电位（ＭＤＰ）及最大除极速率（Ｖｍａｘ）显著降低；硒代蛋氨酸使复极化时程（ＡＰＤ１０、ＡＰＤ５０、ＡＰＤ９０）缩短，动作电位发放频率（ＡＰＦ）加快；而亚硒酸钠在４．０ｍｇ／Ｌ硒剂量时使所有的ＡＰＤ均延长，动作电位发放频率减慢，在作用剂量为１．０、２．０ｍｇ／Ｌ硒时，使ＡＰＤ１０延长，而ＡＰＤ５０、ＡＰＤ９０缩短。表明两种硒化合物均具有Ｃａ２＋通道阻滞作用，而亚硒酸钠还具有Ｋ＋通道阻滞作用     

硒锗联合对酒精致大鼠肝脏脂质过氧化的影响

采用体外和体内实验以酒精诱导大鼠肝脏脂质过氧化为模型，研究了（Ｎａ＿２ＳｅＯ＿３）和锗（羧乙基锗倍半氧化物，Ｇｅ－１３２）联合应用的协同抗氧化作用。结果表明，酒精在体外和体内均可导致大鼠肝脏脂质过氧化。体外研究发现将硒和锗同时使用时（Ｎａ＿２ＳｅＯ＿３，２０μｍｏｌ／Ｌ＋Ｇｅ－１３２，１０．５ｍｍｏｌ／Ｌ），表现出比使用相同剂量单一的硒Ｎａ＿２ＳｅＯ＿３，２０μｍｏｌ／Ｌ）或锗（Ｇｅ－１３２，１０．５ｍｍｏｌ／Ｌ）具有更强的抗氧化作用。体内研究将硒和锗剂量减半同时使用（Ｎａ＿２ＳｅＯ＿３，０．０５５ｍｇ／ｋｇ＋Ｇｅ－１３２，１００ｍｇ／ｋｇ），具有类似如单一的较高剂量硒（Ｎａ＿２ＳｅＯ＿３，０．１１ｍｇ／ｋｇ）的抗氧化作用和比使用单一的较高剂量锗（Ｇｅ－１３２，２００ｍｇ／ｋｇ）更强的抗氧化作用。本次研究结果表明硒（Ｎａ＿２ＳｅＯ＿３）和锗（Ｇｅ－１３２）在体外及体内均具有协同抗氧化作用。     

丁烯酸内酯对心肌细胞跨膜电位的影响及硒的保护作用

丁烯酸内酯对培养的Ｗｉｓｔａｒ大鼠乳鼠心肌细胞动作电位呈双相性效应，即在１００ｍｇ·Ｌ－１以下时使动作电位幅值、超射、阈电位、最大舒张电位、最大除极速率以及复极化时程一致增大；在２００ｍｇ·Ｌ－１以上时使这些参数减小。提示丁烯酸内酯在低剂量时能激活Ｃａ２＋通道，而在高剂量时能抑制Ｃａ２＋通道。含硒０５ｍｇ·Ｌ－１的亚硒酸钠和硒代蛋氨酸能减轻丁烯酸内酯（５００ｍｇ·Ｌ－１）对心肌细胞动作电位的抑制作用。     

硒和维生素E对糖尿病大鼠红细胞[Ca~(2+)]i水平的影响

目的：　观察链脲佐菌素（ＳＴＺ）糖尿病大鼠补充硒（Ｓｅ）和／或维生素Ｅ（ＶＥ）后红细胞内游离钙浓度［Ｃａ２＋ ］ｉ的变化。方法：　用ＳＴＺ制成糖尿病（ＤＭ）大鼠,分为四组：（１）ＤＭ 对照组;（２）Ｓｅ 治疗组;（３）ＶＥ治疗组;（４）Ｓｅ 和ＶＥ治疗组;另有正常对照组,每天以同体积的生理盐水灌胃。实验期为３０ 天,分析血Ｓｅ、ＶＥ及红细胞［Ｃａ２＋ ］ｉ。　结果：　补充Ｓｅ 和／或ＶＥ后,红细胞［Ｃａ２＋ ］ｉ显著下降,与ＤＭ 对照组比较,差异有显著意义（Ｐ＜ ０．０５,Ｐ＜ ０．０１）,以联合用药组降幅较大。血硒水平联合用药组高于其他各组（Ｐ＜ ０．０１）,补Ｓｅ组高于补ＶＥ组和ＤＭ 对照组（Ｐ＜ ０．０１）;血清ＶＥ浓度联合用药组高于ＤＭ 对照组和补Ｓｅ 组（Ｐ＜ ０．０１,Ｐ＜ ０．０５）,而补ＶＥ组血清ＶＥ浓度已恢复至正常水平。　结论：　Ｓｅ和ＶＥ对ＤＭ 大鼠红细胞［Ｃａ２＋ ］ｉ异常升高有明显的抑制作用。     

氟化钠致大鼠肾脏脂质过氧化损伤及亚硒酸钠的保护作用

目的研究氟化钠（ＮａＦ）对大鼠肾脏脂质过氧化作用的影响及亚硒酸钠（Ｎａ２ＳｅＯ３）对氟肾脏毒性的保护作用。方法大鼠经饮水加入ＮａＦ（１５ｍｍｏｌ／Ｌ）或／和Ｎａ２ＳｅＯ３（１５μｍｏｌ／Ｌ）染毒１２０天,观察氟在机体的蓄积、排泄,尿酶活性及肾脏脂质过氧化水平的变化。结果氟染毒后,大鼠血氟水平、尿氟水平、骨氟含量,尿谷氨酰转肽酶（γＧＴ）、Ｎ乙酰βＤ氨基葡萄糖苷酶（ＮＡＧ）、琥珀酸脱氢酶（ＳＤＨ）活性及肾脏活性氧自由基（ＯＦＲＳ）相对浓度、脂质过氧化降解产物丙二醛（ＭＤＡ）含量均显著升高,谷胱甘肽过氧化物酶（ＧＳＨＰｘ）活性及ＧＳＨ含量显著下降。同时补加亚硒酸钠,可促进尿氟排泄,降低血氟水平及骨氟含量,降低尿酶γＧＴ、ＮＡＧ、ＳＤＨ活性和肾脏ＯＦＲＳ、ＭＤＡ含量,同时提高肾脏ＧＳＨＰｘ活性,但对ＧＳＨ含量影响不显著。结论氟化钠引起肾脏损伤与其诱导脂质过氧化作用增强有关,亚硒酸钠对氟化钠致肾脏毒性具有拮抗作用。     

长期低铅染毒对大鼠心肌微粒体膜脂质过氧化影响

分别以醋酸铅（ＰｂＡｃ２）１０，３０和９０ｍｇ／（ｋｇ·ｄ）给雄性ＳＤ大鼠灌胃，连续９周，结果表明心肌微粒体膜（ＭＭＳ）Ｎａ＋，Ｋ＋－ＡＴＰ酶（Ｎａ泵）、超氧化物歧化酶活性、血锌含量降低，ＭＭＳ丙二醛、血和尿铅、胸主动脉Ｃａ２＋含量及ＭＭＳＣａ２＋－ＡＴＰ酶（Ｃａ泵）活性增高，与对照组比较均呈显著性差异。离体大鼠ＭＭＳ单独与不同浓度（０．３，０．６，１．２ｍｍｏｌ／Ｌ）ＰｂＡｃ２共同温育后，除Ｃａ泵活性下降外，出现与体内同样毒性作用。结果提示小剂量ＰｂＡｃ２使ＭＭＳ酶的损害和抗氧化能力降低在铅中毒性心肌损伤中具有重要的作用     

噪声对耳蜗外淋巴中某些离子含量的影响

将１８只豚鼠分为１个对照组和２个暴露组，分别暴露于１１５ｄＢ（ＳＰＬ）、１２５ｄＢ（ＳＰＬ），１．５ｋＨｚ纯音０．５ｈ，以皮层听区诱发电位为检查指标，观察暴露前后动物听力的改变，并测定了耳蜗外淋巴中Ｎａ＋、Ｋ＋、Ｃａ２＋、Ｍｇ２＋离子含量的变化。结果表明，声暴露后各组动物听阈明显提高，且１２５ｄＢ组听力损失明显高于１１５ｄＢ组。１２５ｄＢ声暴露后，耳蜗外淋巴中Ｃａ２＋明显降低，而１１５ｄＢ组与正常对照组相比差异无显著性。声暴露对其它离子的含量没有影响。结果提示Ｃａ２＋可能与声损伤，特别是与永久性听力损失有关。     

富硒香菇活性多糖对实验大鼠免疫缺陷干预及其影响因素研究

为证明含富硒香菇多糖（Ｓｅ－ＬＥＮ）对大鼠免疫调节及Ｔ细胞亚群增殖的提升作用。通过建立免疫缺陷 Ｓｅ－ＬＥＮ干预。采用流式细胞术观察Ｔ细胞亚群等的变化。结果表明：干预组对淋巴细胞、ＣＤ３＋、ＣＤ４＋的增殖有明显的促进作用,脾指数、胸腺指数明显增加。１／５常剂量组上述结果低于对照,接近模型组,促进ＬＹＭ增殖的起始时间于干预１周后即可产生,提示：Ｓｅ－ＬＥＮ具有增强细胞免疫调节功能,显著地促进ＣＤ４＋     

Toxicity of organic and inorganic selenium to mallard ducklings

The toxicity of selenomethionine and sodium selenite to mallard ducklings (Anas platyrhynchos) was measured by feeding each form from hatching to six weeks of age at dietary concentrations of 0, 10, 20, 40, and 80 ppm selenium. At 80 ppm selenium, sodium selenite caused 97.5% mortality by six weeks and selenomethionine caused 100% mortality. At 40 ppm, these two forms of selenium caused 25 and 12.5% mortality. No mortality occurred at 10 or 20 ppm. Diets containing 20, 40, or 80 ppm selenium in both forms caused decreases in food consumption and growth. The only statistically significant effect of 10 ppm selenium was with sodium selenite, which resulted in larger livers than controls. Selenomethionine was more readily stored in the liver than sodium selenite at levels above 10 ppm selenium in the diet. Based on comparisons of residues of selenium in livers of surviving and dead ducklings, concentrations in the liver were not diagnostic of death due to selenium poisoning. Because both forms of selenium resulted in severe reductions in food consumption, selenium-induced starvation may have been related to duckling mortality. It was not clear whether either form of selenium at 10 ppm in the diet resulted in a leveling off of selenium concentrations in the liver within six weeks.     

硒对镉诱导的离体大鼠肝细胞DNA损伤的作用

目的　研究亚硒酸钠对氯化镉诱导的离体大鼠肝细胞DNA损伤的影响。方法　用8 75 μmol/L、17 5 0 μmol/L和 35 0 0 μmol/L的亚硒酸钠分别与 8 75 μmol/L、17 5 0 μmol/L和 35 0 0μmol/L的氯化镉联合作用 ,用单细胞凝胶电泳检测大鼠肝细胞DNA损伤。 结果　 8 75 μmol/L的亚硒酸钠对 8 75 μmol/L、17 5 0 μmol/L和 35 0 0 μmol/L的氯化镉引起的DNA损伤都有拮抗作用 ;17 5 0 μmol/L的亚硒酸钠对 17 5 0 μmol/L和 35 0 0 μmol/L的氯化镉显示拮抗作用 ,而对 8 75μmol/L氯化镉拮抗作用不明显 ;当亚硒酸钠为 35 0 0 μmol/L时 ,则对 8 75 μmol/L、17 5 0 μmol/L和35 0 0 μmol/L的氯化镉没有明显拮抗作用。从氯化镉的角度 ,当氯化镉为 8 75 μmol/L时 ,只有8 75 μmol/L亚硒酸钠拮抗作用最明显 ;当氯化镉为 17 5 0 μmol/L和 35 0 0 μmol/L时 ,8 75 μmol/L和 17 5 0 μmol/L的亚硒酸钠有拮抗作用 ,17 5 0 μmol/L的亚硒酸钠的拮抗作用又优于 8 75 μmol/L的亚硒酸钠。结论　一定剂量的亚硒酸钠拮抗一定剂量的氯化镉引起的DNA损伤与亚硒酸钠的剂量有关 ,随剂量增加 ,拮抗作用下降 ,而且也与亚硒酸钠和氯化镉的相对剂量有关。     

Vitamin B6 dependence of selenomethionine and selenite utilization for glutathione peroxidase in the rat.

The biological availability of selenium from sodium selenite and selenomethionine for glutathione peroxidase activity was studied. Rats were fed ad libitum for 2 weeks a basal diet deficient in both selenium and vitamin B6, and then for the subsequent 2 weeks the same diet supplemented with vitamin B6 (2.5 micrograms as pyridoxine-HCl/g diet) or selenium (2 microgram/g diet) or both. In the presence of vitamin B6, selenite and selenomethionine increased equally the glutathione peroxidase activity in both the liver and erythrocytes above that of selenium-unsupplemented controls. In the absence of vitamin B6, selenomethionine was less effective in the liver and ineffective in the erythrocytes while selenite was equally effective in both tissues and was as effective as in the presence of vitamin B6. These results indicate that selenite selenium is readily available for glutathione peroxidase induction as compared with selenomethionine, and establish that vitamin B6 is involved in the metabolism of selenomethionine to supply selenium for glutathione peroxidase.     

Selenium utilization during human lactation by use of stable-isotope tracers

We examined utilization of selenomethionine (SeMet) and selenite in six lactating (L) and six nonlactating (NL) women, 2-3 mo postpartum, and seven never-pregnant (NP) women by use of stable-isotope tracers. All groups had similar selenium status at the start of the study. Significantly more selenium from SeMet than from selenite was absorbed and appeared in plasma in all groups. Milk contained more selenium from apparently absorbed SeMet than from selenite. More selenium from apparently absorbed selenite than from SeMet appeared in urine of NP and NL subjects whereas L subjects had approximately the same amount of selenium from apparently absorbed selenite and SeMet in their urine. All groups retained significantly more selenium from SeMet than from selenite; L women retained more selenium from selenite than did the other two groups. Absorption and retention of selenium from SeMet in L women did not appear to be significantly different from that in other women, suggesting that selenium requirements during lactation are increased mainly because of milk losses.     

The importance of nutritional support.

Selenium supplements contain selenium in different chemical forms. In the majority of supplements, the selenium is present as selenomethionine. However, in multivitamin preparations, infant formulas, protein mixes, weight-loss products and animal feed, sodium selenite and sodium selenate are predominantly used. In some products, selenium is present in protein- or amino acid chelated forms; in still others, the form of selenium is not disclosed. Current evidence favors selenomethionine over the other forms of selenium. Extradietary supplementation of selenium at the dosage of 200 micrograms per day is generally considered safe and adequate for an adult of average weight subsisting on the typical American diet.     

Bioavailability of selenium to residents in a low-selenium area of China

For 8 wk 5 groups of 10 men each were given 0.5 g/day DL-methionine, 150 micrograms Se/day as sodium selenite with or without methionine or 150 micrograms Se/day as selenomethionine with or without methionine. Twenty subjects received placebo as controls. Initially plasma Se rose more rapidly than RBC Se. Increases in Se levels were significantly greater with selenomethionine than with the selenite supplement. In the placebo and methionine supplemented groups neither plasma nor RBC Se varied significantly over the course of the study. Supplementation with selenium resulted in marked increases in plasma and RBC GSH-Px within 2 and 4 wk, respectively. Plasma and RBC GSH-Px activity did not differ significantly between Se-supplemented groups. These studies suggest that selenomethionine-Se was more effective in raising plasma and RBC Se than was selenite-Se. Methionine supplements may increase the bioavailability of selenium in severely deficient subjects.     

Comparative studies of selenium-75 (selenite and selenomethionine) absorption from various milk diets in suckling rats

Selenium (Se) absorption was studied in human milk, bovine milk and infant formula (Similac) using suckling rats as a model. The effect of age on Se absorption from the three milk diets extrinsically labeled with 75Se, either as selenite or selenomethionine, was also investigated. Milk diets were fed by gastric intubation and the radioactivity in the carcass, gastrointestinal tract and the liver were measured 3 h after feeding. There was no difference in [75Se]selenite absorption from the three milk diets between 8-20 d of age. However, significantly higher quantity of 75Se was absorbed from all three milk diets by 20-d-old rats than by the younger rats (46 vs. 32%). This increase in [75Se]selenite absorption with advancing age is opposite to what has been found for most other trace elements. When rats were fed milk diets labeled with [75Se]selenomethionine, the absorption of 75Se was approximately twofold higher in all age groups compared with 75Se absorption from selenite. No difference in [75Se]selenomethionine absorption existed among the three milk diets in 8- or 10-d-old suckling rats. However, at 15 d of age [75Se]selenomethionine absorption from human milk was higher (82%) than from either bovine milk (72%) or infant formula (72%). Between 8 and 20 d of age, absorption of [75Se]selenomethionine from the three milk diets decreased with advancing age. Adding sodium selenate to increase the total nonradioactive Se of human milk, bovine milk (endogenous plus the added selenium) did not affect the absorption of either [75Se]selenomethionine or [75Se]selenite.     

镰刀菌毒素DON对心肌细胞膜电位的影响及硒的保护效应

目的 观察镰刀菌毒素单端孢霉烯族化合物脱氧雪腐镰刀菌烯醇(DON)对培养心肌细胞动作电位的影响及亚硒酸钠的保护效应。方法 取新生1～2d龄Wistar大鼠,分离心肌细胞,培养基为80％DMEM与20％小牛血清,于37℃,在含5％CO2与95％空气的培养箱内进行培养,于培养后第4天,引导心肌细胞动作电位为加入毒素前对照,然后向培养基中分别加入50、100和200mg／L DON,以观察不同剂量DON对心肌细胞动作电位的影响。在培养基中加入含0．5mg／L硒的亚硒酸钠,继续培养16h后,观察硒对DON致心肌细胞膜电位改变的保护作用。结果 DON使心肌细胞去极化过程发生改变,动作电位(APA)、最大除极速度(Vmax)、超射(OS)及阈电位(TP)均减小,部分参数指标存在较明显的剂量效应关系。OS在DON为50mg／L时出现增高现象。复极化过程的变化,复极动作电位时程(APD)明显延长;最大舒张电位(MDP)减小;动作电位发放频率(APF)受到明显的抑制,且存在明显的剂量依存关系。在培养基中加入含0．5mg／L硒的亚硒酸钠,继续培养16h后,200mg／LDON对其心肌细胞动作电位的抑制作用明显减弱,但部分参数(APA、Vmax、OS、TP、APD90及APF)没有完全保持在正常对照组水平,亚硒酸钠不能完全对抗DON引起的心肌细胞动作电位的改变。结论 DON能抑制大鼠培养心肌细胞的跨膜电位,初步表明亚硒酸钠可减轻DON对心肌动作电位的影响,呈现明显的保护作用。     

Nutritional selenium supplements: product types, quality, and safety

Selenium supplements contain selenium in different chemical forms. In the majority of supplements, the selenium is present as selenomethionine. However, in multivitamin preparations, infant formulas, protein mixes, weight-loss products and animal feed, sodium selenite and sodium selenate are predominantly used. In some products, selenium is present in protein- or amino acid chelated forms; in still others, the form of selenium is not disclosed. Current evidence favors selenomethionine over the other forms of selenium. Extradietary supplementation of selenium at the dosage of 200 micrograms per day is generally considered safe and adequate for an adult of average weight subsisting on the typical American diet.