The effect of Zn2+ on glucose 6-phosphate dehydrogenase activity from Bufo arenarum toad ovary and alfalfa plants

The effect of Zn2+ on glucose 6-phosphate dehydrogenase (G6PD) activity was monitored in samples from Bufo arenarum toad ovary and alfalfa plants, in the search for a possible new bioindicator able to detect levels of exposure through contaminated soils, and also to elucidate possible similarities between the enzyme from animal and plant tissues. The in vivo effect was evaluated after exposure of the toads to the metal in Ringer solution during 30 days and after 10 days of treatment in 6 weeks old plants, cultured under laboratory conditions. In vitro effects were measured in different extracts from control samples and partially purified enzyme from ovarian tissue as well as in different extracts from control alfalfa plants, by addition of the metal to the reaction mixture containing the enzyme. G6PD from toad ovary was noncompetitively inhibited by zinc both in vivo and in vitro, under all the experimental conditions studied. A kinetic analysis of the enzyme activity showed that the Michaelis-Menten constant (Km) was not modified, while maximal velocity (Vmax) decreased as the consequence of treatment. It was not possible to obtain a dose-response curve for the effects of Zn2+ on G6PD from alfalfa whole plants, measured in vivo or in vitro. Only leaf extracts evidenced a possible relationship between treatment with the metal and G6PD activity alteration. The results agree with a possible role for G6PD as a biomarker of effect and exposure to Zn2+ in B. arenarum ovarian tissue but not in alfalfa plants.     

Erythrocyte defects and parasitemia density in patients with Plasmodium falciparum malaria in Buenaventura, Colombia]

OBJECTIVES: To determine the prevalence of some erythrocyte defects and to evaluate the relation that that has with parasitemia density in individuals diagnosed with Plasmodium falciparum malaria in a population in the Pacific coastal region of Colombia. METHODS: This prevalence study was carried out with 242 persons with P. falciparum malaria who had gone for consultation at the Program of Tropical Diseases diagnostic center in the city of Buenaventura, Colombia. The parasitemia levels were measured, and also determined was the presence of congenital erythrocyte defects (glucose-6-phosphate dehydrogenase (G6PD) deficiency, abnormal hemoglobins, and thalassemias) and of other factors possibly related to parasitemia levels. RESULTS: The prevalence of erythrocyte defects was 26.4% (95% confidence interval, 21.0%-32.5%), which was similar to what had been found in previous studies in the same area of Colombia. In the multiple regression models, individuals with sickle cell anemia or a complete deficiency of G6PD had a lower density of parasitemia than did persons without any erythrocyte defect. After adjusting for other variables of interest, the risk of high parasitemias was lower in persons with sickle cell anemia (odds ratio = 0.30) and individuals with a complete deficiency of G6PD (odds ratio = 0.72). CONCLUSIONS: Our results confirm the high prevalence of erythrocyte defects in Colombia's Pacific coastal region, in a population with ethnic characteristics that are similar to those of some populations in West Africa. Our results also lend support for the existence of innate resistance to malaria among carriers of hemoglobin AS and in persons with G6PD deficiency.     

Depression of erythrocyte glucose-6-phosphate dehydrogenase (G6PD) activity in enteric fever

Ninety adult Indian typhoid and paratyphoid fever (enteric fever, EF) patients and 91 controls were tested for glucose-6-phosphate dehydrogenase (G6PD) deficiency using the fluorescent spot test (FST) and the quantitative methaemoglobin reduction test ( QMRT ). There was a threefold higher incidence of G6PD deficiency in North Indian EF patients (10.6%) than in controls (3.6%) (P = 0.15) which may be attributable to the greater morbidity of the G6PD-deficient EF patients; six of nine had haemolytic anaemia. A transient depression of mean erythrocyte G6PD activity was observed in a subgroup of 49 non-deficient EF patients in whom the spectrophotometric G6PD assay was done. It did not appear to be related to reticulocyte count, chloramphenicol therapy, or differences in leucocyte contamination of the haemolysate used for the G6PD assay. If this depression of G6PD activity occurs in deficient patients as well, it may help to explain the haemolysis seen in them during EF. Of the three tests used, the QMRT and the spectrophotometric assay clearly identified G6PD deficiency in males during haemolysis, whereas the FST was unreliable in this situation.     

葡萄糖6磷酸脱氢酶缺乏与新生儿高胆红素血症发生率关系探讨

目的:探讨葡萄糖6磷酸脱氢酶(G6PD)缺乏与新生儿高胆红素血症发生率及发病时间的关系。方法:对近年来本院产科分娩的新生儿脐血进行G6PD定量测定,对G6PD活性缺乏的患儿,按性别和缺乏程度分组调查其高胆红素血症发生率和发病时间。结果:①G6PD缺乏的患儿高胆红素血症发生率极显著高于对照组的新生儿。②在G6PD缺乏的患儿中,男性G6PD缺乏程度极显著低于女性(P<0.01);男性高胆红素血症发生率极显著高于女性(P<0.01);G6PD缺乏程度不同的患儿高胆红素血症发生率有显著差别(P<0.05)。③G6PD缺乏的患儿高胆红素血症的发病时间主要在出生后的1周内。结论:G6PD缺乏是新生儿发生高胆红素血症的病因之一。在G6PD缺乏的患儿中,高胆红素血症发生率具有男性多于女性、G6PD缺乏程度越重发病率越高、发病的高峰时间在出生后的2~4天。     

Prevalence of classic erythrocyte polymorphisms among 749 children in southern highland Rwanda

Classic erythrocyte polymorphisms were assessed by PCR-based methods among 749 children in southern highland Rwanda. Sickle cell trait, glucose-6-phosphate dehydrogenase (G6PD) deficiency, and α(+)-thalassaemia were observed in 2.8%, 9.6%, and 15.1%, respectively. Malariologic parameters did not correlate with these traits. Haemoglobin concentrations were significantly reduced in α(+)-thalassaemia but only homozygosity (0.8%) was a rare cause of anaemia in this population. The frequencies of malaria-protective polymorphisms reflect the high altitude (1700-1800 metres) of the study area. α(+)-thalassaemia and G6PD deficiency have previously been underestimated in Rwanda which may be of importance in the diagnosis and treatment of common childhood diseases.     

Short-term modulation of lipogenesis by macronutrients in rainbow trout (Oncorhynchus mykiss) hepatocytes

Rainbow trout (Oncorhynchus mykiss) hepatocytes were cultured under simulated conditions of varying nutritional status to explore the short-term modulation by dietary substrates of the main lipogenic enzymes: glucose-6-phosphate dehydrogenase (G6PD), malic enzyme (ME), ATP-citrate lyase (ACL), acetyl-CoA carboxylase (ACoAC) and fatty acid synthetase (FAS). Primary cultures were individually exposed to varying amounts of glucose, hydrolysed casein and long-chain polyunsaturated fatty acids (PUFA) for 12 h. A second set of experiments was designed to evaluate the effects of mixing different relative amounts of these macronutrients in the culture medium. Glucose concentrations of up to 20-25 mm showed a stimulatory effect on G6PD, ME, ACL and ACoAC activity while an earlier inhibitory effect on FAS was observed at 10-20 mm glucose The use of hydrolysed casein as a nutritional source of amino acids inhibited the activity of FAS and ME and stimulated G6PD, ACoAC and ACL activity Low levels of linolenic acid exerted a stimulatory effect on all the lipogenic enzymes assayed with the exception of FAS, and increased amounts showed some inhibition of lipogenic activities Eicosapentaenoic acid and docosahexaenoic acid showed a similar effect, although the former strongly inhibited FAS activity while the latter showed greater potential to inhibit ACoAC and G6PD. A complete change in the relative levels of glucose, hydrolysed casein and PUFA in turn led to changes in the enzyme activity patterns observed. The present study shows the feasibility of exploring the direct regulation of lipogenesis in isolated fish cells by varying the relative amounts of main macronutrients, mimicking in vivo dietary conditions. It is felt that such an approach may serve to investigate the macronutrient regulation of other metabolic pathways.     

Occupational lead exposure and screening of glucose-6-phosphate dehydrogenase polymorphism: useful prevention or nonvoluntary discrimination?

Objective: To discuss regulatory guidelines excluding subjects with erythrocyte glucose-6-phosphate dehydrogenase (G6PD) deficiency from lead-exposed jobs in the light of epidemiology findings on the mortality of these subjects. Methods: Two mortality follow-up studies were conducted. The first comprised 1979 male subjects newly identified as G6PD-deficient during a 1981 screening of the G6PD polymorphism among the general population in Sardinia, Italy. The second comprised 1080 male workers employed in maintenance and production departments of a lead smelting plant, who were divided into two subcohorts by erythrocyte G6PD phenotype. Results: As compared with the general male population, G6PD-deficient subjects had significantly fewer deaths than expected from ischemic heart disease (standardized mortality ratio (SMR)=28; 95% CI 10–62), cerebrovascular diseases (SMR=22; 95% CI 6–55), and liver cirrhosis (SMR = 12; 95% CI 0–66). Among lead smelters the standardized mortality rates from cardiovascular diseases and all cancers observed among the G6PD-deficient subcohort were lower than those seen among subjects with the wild-type G6PD. No death from disease of the blood and hematopoietic system was observed among G6PD-deficient subjects in these two follow-up studies. Conclusions: These studies did not provide evidence of hypersensitivity to lead hematotoxicity among G6PD-deficient individuals at exposure levels within the current standards. Provided that workplace exposure complies with current standards, the hypothetical benefit of excluding G6PD-deficient individuals from lead-exposed jobs should be weighted against the loss of personal abilities and the economic damage in a social environment with diffuse unemployment. Received: 14 July 1997 / Accepted: 17 October 1997     

Effects of long-term exposure to Cu2+ and Cd2+ on the pentose phosphate pathway dehydrogenase activities in the ovary of adult Bufo arenarum: possible role as biomarker for Cu2+ toxicity

The effects of copper and cadmium on metabolism through the pentose phosphate pathway were evaluated in Bufo arenarum toad ovary. The effects of the two metals on dehydrogenases from this pathway were evaluated by three experiments: (1) in samples obtained from control females with addition of the metals to the reaction mixture (in vitro), (2) in samples obtained from control females and after long-term exposure of females to 4 and 100 microg/L of Cu or Cd in the incubation media (in vitro after exposure to the metals in vivo), and (3) 14CO2 production through the pentose phosphate pathway was evaluated after [U-14C]glucose microinjection on ovulated oocytes (in vivo after microinjection of the metals). Results from (1) evidenced inhibition of both enzyme activities but only above 1.5 mM Cu and Cd added to the reaction mixture. In (2) both glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities decreased in samples from the ovaries of females exposed in vivo to Cu, in a concentration-dependent manner (up to 90% in females exposed to 100 microg/L Cu: 2.12 +/- 1.57 NADPH micromol/min microg protein x 10(-5) vs 19.97 +/- 8.54 in control females). Cd treatment of the toads only rendered an inhibitory effect on 6-phosphogluconate dehydrogenase activity after exposure to 4 microg/L of the bivalent cation. (3) In vivo 14CO2 evolution significantly decreased in oocytes coinjected with 6.3 x 10(-3) mM Cu (calculated intracellular final concentration of the metal injected) and radioactive glucose. Cu and Cd concentration in samples from exposed females were always under detection limit by particle-induced X-ray emission. The results presented here are in agreement with a role for both glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities determination as biomarkers of effect and exposure for Cu but not for Cd toxicity.     

Selenium, vitamin E and the response to swimming stress in the rat.

Experiments were conducted to determine the effects of exercise on rat glutathione peroxidase system enzymes and lipid peroxidation among animals supplemented and unsupplemented with selenium (Se) and vitamin E (E). Liver, muscle and blood were taken before, immediately after and 24 hours after exercising to exhaustion by swimming. No effect of exercise was found on muscle or liver enzymes, although exercise resulted in depressed glutathione reductase (GR) and glucose-6-phosphate dehydrogenase (G6PD) activities in erythrocytes immediately after exercise. Dietary Se supplementation did result in increased hepatic muscle and erythrocyte glutathione peroxidase activity, and decreased hepatic GR, G6PD and "malic enzyme" activities. Thiobarbituric acid reactive substances, and indicator of lipid peroxidation, increased in liver and muscle subsequent to exercise. This increase was reduced in liver, but not eliminated, by dietary E supplementation. The increase was not affected by dietary E in muscle, nor by dietary Se in either tissue.     

Regulation of glucose-6-phosphate dehydrogenase and malic enzyme in liver and adipose tissue: effect of dietary trilinolein level in starved-refed and ad libitum-fed rats.

The responses of glucose-6-phosphate dehydrogenase (G6PD) (EC 1.1.1.49) and malic enzyme (ME) (EC 1.1.1.40) were studied in liver and adipose tissue of rats fed for 2 days a high glucose diet containing levels of synthetic trilinolein ranging from 0 to 25% (w/w) of the diet (trilinolein was substituted for glucose). One group of rats was starved for 2 days before the trilinolein-containing diets were fed (starved-refed); a second group of rats was fed a fat-free diet for 7 days before the trilinolein-containing diets were fed (ad libitum). Liver G6PD activity decreased exponentially and liver ME activity decreased linearly with increasing dietary trilinolein in starved-refed rats, but did not decrease significantly in ad libitum fed rats. Total liver lipid decreased exponentially with increasing trilinolein in starved-refed rats, but increased exponentially in ad libitum fed rats. Adipose tissue G6PD and ME activities decreased slightly with increasing trilinolein in starved-refed rats, but did not decrease in ad libitum fed rats. When the data were adjusted by analysis of covariance for differences in glucose intake, the liver responses in starved-refed rats were still significant but the adipose tissue responses were not, indicating that the responses of adipose tissue (but not of liver) may have resulted from decreased glucose intake rather than from increased trilinolein intake. The results suggest that dietary trilinolein inhibits the characteristic increase in liver G6PD, ME and total lipids upon starvation-refeeding. However, after the levels of these parameters have been increased by feeding a fat-free diet they cannot be decreased by dietary trilinolein in 2 days.     

In vitro effects of ethanol, acetaldehyde and fatty acid ethyl esters on human erythrocytes

In vitro experiments were performed to determine if ethanol was metabolized by human erythrocytes and to investigate if ethanol or its metabolites, acetaldehyde and fatty acid ethyl esters, affected erythrocyte morphology and stability. No detectable metabolism of ethanol was found in erythrocytes, although ethanol itself caused an elevated rate of spontaneous haemolysis in erythrocyte preparations. Physiologically attainable levels of ethanol were found to stabilize erythrocytes against haemolysis induced by sodium hypochlorite, and the presence of ethanol caused a decrease in erythrocyte reactive oxygen species levels, although the mechanism for such a process is unknown. Both physiologically attainable and higher levels of acetaldehyde had no effects on erythrocyte morphology and stability even after a 16 h exposure. Fatty acid ethyl esters caused structural changes and instability in erythrocytes in vitro, but whether such changes occur in vivo has not been established. The results of these studies suggest that the deleterious effects of ethanol consumption on erythrocytes in vivo may be, at least in part, the result of direct effects of unmetabolized ethanol on erythrocyte components.     

Effect of 2,4-dichlorophenoxyacetic acid on the activities of some metabolic enzymes for generating pyridine nucleotide pool of cells from mouse liver

2,4-Dichlorophenoxyacetic acid (2,4-D), which is a plant auxin analogue, is lethal to broad leaved weeds within days at high dosages and is considered as having low toxicity to mammals. Some studies have reported that exposure to this compound may cause damage to organs such as liver. The aim of this study was to investigate the effects of 2,4-D in mouse liver on chromosomes as well as hexokinase (HK), glucose-6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGD), lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) which are required for the generation of the pyridine nucleotide pool. The experiments were carried out with a 2,4-D group, an ethanol control for 2,4-D, and saline group for ethanol control group on three generations of mice. Only female parents were given 2,4-D during the gestation period, lactation period and for 33 days following the lactation period. In females of the first cross, 2,4-D caused a significant increase in the activity of LDH, and ethanol alone caused a significant increase in the activities of HK and LDH. In the male offspring of the first cross maternal, 2,4-D caused a significant increase in the activity of LDH, and ethanol alone caused a significant decrease in the activity of 6PGD. In the female offspring of the first cross maternal, ethanol caused a significant increase in the activities of G6PD and MDH. In the female offsprings of the third cross maternal, 2,4-D caused a significant increase in the activity of MDH. No gross morphological changes were observed in internal organs, such as liver, kidney and spleen of the affected animals. Also, a chromosomal study from bone marrow cells indicated no anomalies in chromosomal sets and structures. As a result, 2,4-D had an effect on the first cross maternal and their offsprings. The compound did not affect the parameters studied except MDH enzyme activity in the second and third generation of mice.     

深圳地区育龄人群G6PD基因突变谱特征分析

目的:分析深圳地区育龄人群葡萄糖-6磷酸脱氢酶(G6PD)缺乏症的发生率及基因突变特征。方法:采集深圳地区体检育龄夫妇外周血样本,采用葡萄糖-6磷酸脱氢酶/6-磷酸葡萄糖酸脱氢酶(G6PD/6GPD)比值法、突变阻滞聚合酶链扩增系统(ARMS-PCR)结合二代测序(NGS)全序列分析方法,对样本进行G6PD基因突变检测和分析。结果:5640例样本G6PD酶活性异常比例为6.4%(360/5640),G6PD基因突变比率为7.8%(442/5640)。酶活性正常的5280例样本中(男性1331例、女性3949例)基因突变占1.8%(96/5280),男女性样本漏诊率分别为0.3%(3/1331)和2.4%(93/3949),而在1109例G6PD酶活性异常样本(包括之前收集的749例阳性样本)中,有25例样本未发现基因变异,误诊率2.2%(25/1109)。本研究共检出23种基因突变类型,发现c.460A>G、c.226A>C、c.-6T>C、c.452C>G 4种未见报道的基因突变类型。结论:深圳地区常见G6PD缺乏症致病基因突变类型主要为c.1376 G>T、c.1388 G>A、c.95 A>G、c.871 G>A、c.392 G>T、c.1024C>T 6种,与中国人G6PD缺乏症常见基因突变类型基本一致。本研究发现4例尚未见报道的可能致病性突变,其与酶活性缺乏的具体关系尚需进一步深入研究。     

The multiple forms of liver glucose-6-phosphate dehydrogenase in spontaneously and prematurely weaned rats

The various molecular species of rat liver glucose-6-phosphate dehydrogenase (G6PD) were assayed during and immediately after weaning. Three dimeric forms were detected, but tetramers and hexamers were absent. Spontaneous weaning to the maternal diet was associated with an increase in the percentage of G6PD activity contributed by G6PD-III, at the expense of G6PD-I and G6PD-II. These changes occurred sooner when the rats were prematurely weaned on postnatal day 17. The percentage distribution of G6PD activity among the dimeric forms was not correlated with liver glutathione (GSH) content, or with the ratio of G6PD activity to GHS levels, suggesting that liver GSH content as such may not be the primary factor responsible for regulating the proportions of G6PD activity present in each form. It appears that interconversions involving the tetrameric and hexameric forms of G6PD, probably do not contribute to the control of hepatic G6PD activity during the weaning period. The data also suggest that the rise in hepatic G6PD activity attendant on weaning may be associated with decreased enzyme degradation.     

云南保山地区汉族7岁以下儿童地中海贫血与G6PD缺乏症调查分析

目的:了解云南省保山地区7岁以下汉族儿童地中海贫血和G6PD缺乏症的现状。方法:地中海贫血检测对1358名儿童进行血细胞分析,用PH8.6缓冲液醋酸纤维薄膜做电泳分析;G6PD缺乏症检测采用改良葡萄糖6-磷酸脱氢酶(G6PD)测定比值法(手工操作法)进行检测。结果:β一地贫检出率5.2%,α-地贫检出率4.6%,G6PD缺乏症检出率0.7%。结论:地贫在保山地区汉族儿童中属高发,G6PD缺乏症阳性率在减少。地贫和G6PD缺乏症的人群地理分布与历史上疟疾流行的地理分布存在着一定的相关性。     

Effect of pancreatectomy or adrenalectomy on the responses of rats to meal-feeding.

The effects of partial pancreatectomy or adrenalectomy and insulin or corticosterone replacement on the responses of rats to meal-feeding were studied. Partial pancreatectomy lowered glucose-6-phosphate dehydrogenase (G6PD) and malic enzyme (ME) activities and resulted in higher blood glucose levels. Partial pancreatectomy did not affect the ability of the animals to adapt to meal-feeding. Insulin supplementation of the pancreatectomized rats restored G6PD and ME activities to those observed in the intact animals and normalized the blood glucose levels in the ad libitum-fed rats. Adrenalectomy decresed the survival of rats subjected to meal-feeding. Eighty percent of the rats died when meal-fed a high glucose diet. Survival was improved when either a 66.5% starch diet or a 40.5% fat diet was substituted for the 66.5% glucose diet. Adrenalectomized meal-fed animals fed 66.5% glucose had higher G6PD and ME activities and higher liver lipid levels than both the adrenalectomized ad libitum-fed and the sham-operated meal-fed rats. Glucocorticoid supplementation lowered G6PD activity in the adrenalectomized meal-fed rats but had no effect on ME activity or liver lipid. Meal-fed adrenalectomized rats had lower liver and serum cholesterol levels than meal-fed intact rats and ad libitum-fed adrenalectomized rats. These cholesterol levels were increased with glucocorticoid supplementation. It was concluded that adaptation to meal-feeding involves an adrenal response to the periodic absence of dietary energy intake, and that the degree of involvement of this response is determined by the composition of the diet.     

8140例新生儿脐带血G6PD筛查结果分析

目的研究新生儿脐带血的葡萄糖-6-磷酸脱氢酶男性缺乏率和酶活性测定法在女性杂合子中的检出率。方法全自动生化分析仪测定G6PD酶活性,根据测定的结果,计算出新生儿脐带血的基因频率和女性杂合子的检出率。结果新生儿脐带血的G6PD缺乏症在本地区发病率为3.07%,男性的G6PD缺乏率是4.04%,酶活性测定法在女性杂合子中的检出率是21.95%。结论采用酶活性检测法在女性杂合子检出率中效果不理想,这有利于在遗传咨询和新生儿出生缺陷等方面提供更全面的信息。     

库存血G6PD活性降低对新生儿高胆红素血症换血治疗效果的影响

目的探讨新生儿高胆红素血症换血治疗时库存血G6PD活性降低对治疗效果的影响。方法根据换入的库存血的G6PD活性检测结果将56例接受换血治疗的高胆红素血症新生儿分为两组：库存血G6PD活性降低（G6PD-D）组与库存血G6PD活性正常（G6PD-N）组。比较换血后各时段（0、122、4 h）二组患儿的TSB水平及下降百分比,并对其换血后的光疗时间进行比较。结果与G6PD-N组比较,G6PD-D组患儿换血后的TSB水平下降较慢,换血12及24 h时TSB的下降百分比较小,换血后的光疗时间延长（P〈0.05）。结论高胆红素血症新生儿换血治疗时输入G6PD活性降低的库存血液将使换血后患儿的胆红素水平下降较慢,光疗时间明显延长,建议新生儿换血治疗前对库存血液进行G6PD活性筛查实验。     

Dietary fatty acids on the control of glucose-6-phosphate dehydrogenase and malic enzyme in the starved-refed rat.

The role of dietary unsaturated fat in the control of hepatic glucose-6-phosphate dehydrogenase (G6PD) (EC 1.1.1.49) and malic enzyme (ME) (EC 1.1.1.40) was studied in rats subjected to one or two cycles of starvation-refeeding. Rats starved and refed a control (5% corn oil) diet showed a threefold increase in G6PD activity and a twofold increase in ME activity compared to ad libitum-fed rats. After a second cycle of starvation-refeeding G6PD and ME activities showed fourfold and threefold increases, respectively, as compared to ad libitum-fed rats. Feeding rats diets containing 8% linoleic acid (as triglycerides) prevented the increase in G6PD and ME activities upon starvation-refeeding, diets with oleic, palmitic, and stearic acis when fed did not prevent this increase. Feeding rats various combinations of linoleic, linolenic and oleic acids following starvation prevented the additional increase in G6PD and ME activities after a second starvation-refeeding cycle; however, linoleic acid fed alone during the first refeeding prevented the additional increase in ME activity but not in G6PD activity. It is suggested that the dietary control of these enzymes involves one or more specific polyunsaturated fatty acids.     

Excess dietary vitamin E lowers the activities of antioxidative enzymes in erythrocytes of rats fed salmon oil

In vitro studies suggest that high vitamin E supplementation has prooxidative activity, but very few studies have investigated this effect in vivo. We investigated the effect of excess vitamin E on the antioxidative status of rat erythrocytes and indicators of hemolysis. Six groups of growing male Sprague-Dawley rats were fed purified diets with three different vitamin E doses [100, 1000 and 10,000 mg all-rac-alpha-tocopheryl acetate (TA)/kg diet] and two different dietary fats (salmon oil and lard) for 8 wk. The rats whose diet contained salmon oil and 10,000 mg TA/kg had lower activities of superoxide dismutase (P < 0.05), glutathione peroxidase (P < 0.05), catalase (P < 0.05) and glucose-6-phosphate dehydrogenase (P < 0.05) and a lower concentration of glutathione (P < 0.05) in the erythrocyte cytosol than rats whose diet contained 100 mg TA/kg. The concentration of free hemoglobin and the binding capacity of haptoglobin in plasma, both indicators of in vivo hemolysis, did not differ between rats fed the salmon oil diet with 100 or 10,000 mg TA/kg. In the rats whose diet contained lard, the activities of antioxidant enzymes in erythrocytes and indicators of in vivo hemolysis were independent of the dietary vitamin E concentration. The results of the study suggest that an excessive vitamin E intake, when combined with salmon oil in the diet, lowers the activities of antioxidant enzymes in erythrocytes without affecting in vivo hemolysis.