The measurement of nanograms of tocopherol from needle aspiration biopsies of adipose tissue: normal and abetalipoproteinemic subjects

A method for the analysis of tocopherol in human adipose tissue using high performance liquid chromatography and fluorescence spectrometry is described; results are expressed relative to total triglyceride content measured by the reaction of the methylated fatty acids with hydroxylamine and ferric chloride. The tocopherol contents of adipose tissue obtained at surgery and by the needle aspiration biopsy technic of ambulatory human subjects (who did not take supplemental vitamin E) were found to be virtually identical. The tocopherol content of adipose tissue by the needle aspiration technic was 262 +/- 33 ng tocopherol/mg triglyceride; this value was increased twofold or more in persons ingesting additional vitamin E. Patients with abetalipoproteinemia (ABL) who absorb tocopherol poorly and have extremely low levels of plasma and red blood cell tocopherol also had a low concentration of adipose tissue tocopherol. However, some ABL patients on massive supplementation with vitamin E (approximately 10 g daily) did achieve normal concentrations of adipose tissue tocopherol.     

Altered vitamin E status in Niemann-Pick type C disease

Vitamin E (α-tocopherol) is the major lipid-soluble antioxidant in many species. Niemann-Pick type C (NPC) disease is a lysosomal storage disorder caused by mutations in the NPC1 or NPC2 gene, which regulates lipid transport through the endocytic pathway. NPC disease is characterized by massive intracellular accumulation of unesterified cholesterol and other lipids in lysosomal vesicles. We examined the roles that NPC1/2 proteins play in the intracellular trafficking of tocopherol. Reduction of NPC1 or NPC2 expression or function in cultured cells caused a marked lysosomal accumulation of vitamin E in cultured cells. In vivo, tocopherol significantly accumulated in murine Npc1-null and Npc2-null livers, Npc2-null cerebella, and Npc1-null cerebral cortices. Plasma tocopherol levels were within the normal range in Npc1-null and Npc2-null mice, and in plasma samples from human NPC patients. The binding affinity of tocopherol to the purified sterol-binding domain of NPC1 and to purified NPC2 was significantly weaker than that of cholesterol (measurements kindly performed by R. Infante, University of Texas Southwestern Medical Center, Dallas, TX). Taken together, our observations indicate that functionality of NPC1/2 proteins is necessary for proper bioavailability of vitamin E and that the NPC pathology might involve tissue-specific perturbations of vitamin E status.     

Vitamin E supplementation for the ruminant

Vitamin E is essential for such body functions as growth, reproduction, prevention of various diseases, and for integrity of tissues. The most significantly important result of selenium and vitamin E deficiency is tissue degeneration (e.g. white muscle disease). Vitamin E does not cross the placenta in any appreciable amounts; however, it is concentrated in colostrum. Supplemental vitamin E can greatly increase colostral tocopherol. The importance of providing colostrum rich in vitamin E is essential as both calves and lambs are born with low levels of the vitamin. Vitamin E has been shown to increase performance of feedlot cattle and to increase immune response for ruminant health, including being beneficial for mastitis control. Vitamin E given to finishing cattle at higher than National Research Council (NRC) requirements dramatically maintained the red color (oxymyoglobin) compared with the oxidized metmyoglobin of beef. It appears that supplementation of 500 IU vitamin E per head daily for 84–126 days yields tissue -tocopherol that would maintain a favorable level of oxymyoglobin in meat, thus increasing its value. Vitamin E nutritional status is commonly estimated from plasma concentration, with a high correlation between plasma and liver levels of -tocopherol. The NRC estimates for vitamin E requirements of beef cattle, dairy cattle and sheep to range from 15 to 40 mg kg⁻¹; however, higher levels will likely improve performance, and megadose levels will improve carcass quality.     

Lipid peroxidation products,and vitamin and trace element status in patients with cancer before and after chemotherapy,including adriamycin

Adriamycin is a potent chemotherapeutic agent used in the treatment of human neoplastic diseases. A major side effect limiting the use of this drug is its toxic effect on the heart. Several hypotheses have been proposed to explain the cardiotoxicity of Adriamycin. However, the most plausible hypothesis seems to be the reduction of Adriamycin and free radical production, which induces lipid peroxidation and oxidative damages in the heart. We have thus undertaken this preliminary study to investigate Adriamycin-induced lipid peroxidation by the measurement of plasma thiobarbituric acid reactant materials and antioxidant systems, namely glutathione content, glutathione peroxidase activity, and vitamin and trace element status, in patients with cancer before and after chemotherapy, including Adriamycin. The concentration of thiobarbituric acid reactant materials in plasma of patients with cancer was higher than in controls and was further increased after chemotherapy. Blood glutathione and plasma glutathione peroxidase activity, as well as plasma zinc and selenium in patients with cancer, were decreased, but not further modified by chemotherapy. However, only zinc and selenium levels reached a significant level. In contrast, plasma vitamin E and β-carotene levels were not significantly increased in patients with cancer. Finally, plasma vitamin A and copper levels were not modified either in patients with cancer or by chemotherapy.     

Tocopherol Transfer Protein Sensitizes Prostate Cancer Cells to Vitamin E

Prostate cancer is a major cause of mortality in men in developed countries. It has been reported that the naturally occurring antioxidant α-tocopherol (vitamin E) attenuates prostate cancer cell proliferation in cultured cells and mouse models. We hypothesized that overexpression of the tocopherol transfer protein (TTP), a vitamin E-binding protein that regulates tocopherol status, will sensitize prostate cancer cells to the anti-proliferative actions of the vitamin. To test this notion, we manipulated the expression levels of TTP in cultured prostate cells (LNCaP, PC3, DU145, and RWPE-1) using overexpression and knockdown approaches. Treatment of cells with tocopherol caused a time- and dose-dependent inhibition of cell proliferation. Overexpression of TTP dramatically sensitized the cells to the apoptotic effects of α-tocopherol, whereas reduction (“knockdown”) of TTP expression resulted in resistance to the vitamin. TTP levels also augmented the inhibitory effects of vitamin E on proliferation in semi-solid medium. The sensitizing effects of TTP were paralleled by changes in the intracellular accumulation of a fluorescent analog of vitamin E and by a reduction in intracellular levels of reactive oxygen species and were not observed when a naturally occurring, ligand binding-defective mutant of TTP was used. We conclude that TTP sensitizes prostate cancer cells to the anti-proliferative effects of vitamin E and that this activity stems from the ability of protein to increase the intracellular accumulation of the antioxidant. These observations support the notion that individual changes in the expression level or activity of TTP may determine the responsiveness of prostate cancer patients to intervention strategies that utilize vitamin E.     

Low vitamin E in diet reduces stress resistance of gilthead seabream (Sparus aurata) juveniles

This study investigates the effect of dietary vitamin E on juveniles of gilthead seabream under stressful situations, focusing on the effects on growth, haematology, some immune parameters and plasma cortisol as indicators of stress. Two sardine meal-based experimental diets, one of them supplemented with 150 mg of alpha tocopherol kg(-1) of diet (control) and another one without vitamin E supplementation (diet NE), were assayed under two different stress conditions: overcrowding as a chronic stressor (during 15 weeks) and repetitive chasing as an acute repetitive stressor. Low levels of vitamin E in the diet depleted alternative complement pathway activity [from 167.23 U ml(-1) (control fish) down to 100.99 U ml(-1)] and also nonspecific haemagglutination. Also, fish fed a non-supplemented diet showed an elevation of plasma cortisol basal levels without a stressor influence [from 3.91 ng cortisol ml(-1) plasma (control fish) up to 21.70 ng cortisol ml(-1) plasma]. Low levels of vitamin E in the diet also produced an increase of erythrocyte fragility. Under chronic stress, fish fed the vitamin E-deficient diet showed a reduction in growth and survival, and alterations in haematological parameters, such as an additional haemoconcentration in response to overcrowding when compared with control fish. Under repetitive stress, fish fed the vitamin E deficient diet showed faster elevation of plasma cortisol levels in response to stress and a lower survival rate than control fish. Production of oxygen radicals by blood neutrophils was reduced under repetitive stress in fish fed the non-supplemented diet. These results suggest that fish fed the vitamin E-deficient diet had lower stress resistance.     

Association of tocopherols with circulating autoantibody levels against an oxidized DNA nucleoside in humans

Autoantibodies against oxidized DNA bases are found in vivo and have been used as an indicator of oxidative damage, yet little is known concerning their individual variation and relation to serum micronutrients. Human plasma anti-5-hydroxymethyl-2'-deoxyuridine (HMdU) autoantibody (aAb) levels were repeatedly determined in 41 women and 11 men, and found to have small within-individual variation over time, but large between-individual differences. A positive association in both women (r = .5762, p = .0001) and men (r = .415, p = .2) between plasma total tocopherols and antibody levels was observed. Autoantibody levels were lower in postmenopausal women (8.37 +/- 1.61 vs. 17.18 +/- 2.85 in premenopausal women, p < .01), independently of plasma tocopherol. However, aAb titers in postmenopausal women were still significantly associated with plasma tocopherol levels and adjustment for menopausal status in women yielded a highly significant correlation between HMdU aAb levels and total tocopherol (r = .7342, p = .0001). Plasma malondialdehyde equivalents (MDA), a measure of lipid peroxidation, were also higher in individuals with either high plasma alpha-tocopherol or high beta+gamma-tocopherol levels. The positive association of tocopherols with markers of oxidative damage may reflect a response to the generation of endogenous oxidants associated with enhanced immune function. The decrease in aAb level in postmenopausal women may similarly reflect decreased immune function associated with decreased estrogen levels.     

Circulating levels of α‐tocopherol and retinol in free‐ranging African elephants (Loxodonta africana)

To date, there are no detailed reports of circulating levels of plasma α‐tocopherol and retinol for large samples of free‐ranging African elephants (Loxodonta africana). This survey study measured natural circulating levels of α‐tocopherol as a measure of vitamin E activity and retinol as an indicator of vitamin A activity, in 70 free‐ranging African elephants captured at Kruger National Park as part of a translocation program. Mean levels of α‐tocopherol and retinol were found to be 0.613 ± 0.271 μg/mL and 0.039± 0.007 μg/mL, respectively, and did not vary significantly across sex or age class. Elephants appear to normally have low circulating levels of both these nutrients compared with domestic herbivore species; values from healthy, free‐ranging elephant populations may provide useful data for assessing nutrient status of captive animals. Zoo Biol 18:319–323, 1999.© 1999 Wiley‐Liss, Inc.     

Long-term bromocriptine therapy and predictive tests in acromegaly

The value of predictive tests in bromocriptine therapy and the effects of long-term bromocriptine therapy were investigated in acromegalic patients. In 72 acromegalic patients, there was a tendency for patients with a plasma GH response to TRH or with an elevated basal plasma PRL level, but without a plasma GH response to LHRH, to have a plasma GH response to bromocriptine, though statistical analysis did not reveal a significant difference. Acute and chronic effects of bromocriptine were significantly interrelated, while the chronic effect of bromocriptine and abnormal plasma GH response to TRH or elevated plasma PRL levels were not, in 18 acromegalic patients. These results suggest that the acute bromocriptine test is a better predictor than the TRH test and plasma PRL levels for evaluating the effects of chronic bromocriptine therapy. To maintain the low plasma GH levels, increasing doses of bromocriptine were needed in most patients, and failure to control the elevated GH level despite increasing doses was observed in 2 of 18 patients.     

Serum ex vivo lipoprotein oxidizability in patients with ischemic heart disease supplemented with vitamin E

The decreased oxidizability of plasma lipoproteins is related to the increased vitamin E intake and its association with a relatively lower incidence of coronary heart disease has been proposed. We investigated the effect of the in vivo vitamin E supplementation on the oxidizability of serum lipids in patients with ischemic heart disease and a moderate hypercholesterolemia. Thirty-two patients (16 males and 16 postmenopausal women) participated in this placebo-controlled, randomized trial. They were treated with 400 mg vitamin E/day for 6 weeks. The copper-induced serum lipid oxidizability ex vivo was assessed by measuring conjugated diene formation at 245 nm. We also measured vitamin E, malondialdehyde (MDA) and uric acid concentrations in the plasma. Because of observed significant differences in parameters of serum lipid oxidizability (lag time and maximal rate of oxidation), plasma alpha-tocopherol and MDA levels between male patients and postmenopausal women supplemented with vitamin E, the results were compared between both genders. Six weeks of vitamin E supplementation significantly increased plasma vitamin E levels (by 87 %) in male patients but in postmenopausal women only by 34 %. Concomitantly with increased plasma levels of vitamin E the decrease in plasma MDA levels was observed in male patients (decrease by 20 %; p=0.008), but in postmenopausal women the decrease did not attain statistical significance. Plasma uric acid levels were not apparently changed in placebo or vitamin E supplemented groups of patients. The changes in ex vivo serum lipid oxidizability after vitamin E, supplementation have shown a significantly prolonged lag time (by 11 %; p=0.048) and lowered rate of lipid oxidation (by 21 %; p=0.004) in male patients in comparison with postmenopausal women. Linear regression analysis revealed a significant correlation between plasma vitamin E levels and the lag time (r=0.77; p=0.03) and the maximal rate of serum lipid oxidation (r=-0.70; p=0.05) in male patients. However, in postmenopausal women the correlations were not significant. We conclude that 400 mg vitamin E/day supplementation in patients with ischemic heart disease and a moderate hypercholesterolemia influenced favorably ex vivo serum lipid oxidation of male patients when compared with postmenopausal women. The observed differences between both genders could be useful in the selection of the effective vitamin E doses in the prevention of coronary heart disease.     

Alpha-tocopherol supplementation does not affect monocyte endothelial adhesion or C-reactive protein levels but reduces soluble vascular adhesion molecule-1 in the plasma of healthy subjects

Vascular monocyte retention in the subintima is pivotal to the development of cardiovascular disease and is facilitated by up-regulation of adhesion molecules on monocytes/endothelial cells during oxidative stress. Epidemiological studies have shown that cardiovascular disease risk is inversely proportional to plasma levels of the dietary micronutrients, vitamin C and vitamin E (alpha-tocopherol). We have tested the hypothesis that alpha-tocopherol supplementation may alter endothelial/monocyte function and interaction in subjects with normal ascorbate levels (> 50 microM), as ascorbate has been shown to regenerate tocopherol from its oxidised tocopheroxyl radical form in vitro. Healthy male subjects received alpha-tocopherol supplements (400 IU RRR-alpha-tocopherol/day for 6 weeks) in a placebo-controlled, double-blind intervention study. There were no significant differences in monocyte CD11b expression, monocyte adhesion to endothelial cells, plasma C-reactive protein or sICAM-1 concentrations post-supplementation. There was no evidence for nuclear translocation of NF-kappaB in isolated resting monocytes, nor any effect of alpha-tocopherol supplementation. However, post-supplementation, sVCAM-1 levels were decreased in all subjects and sE-selectin levels were increased in the vitamin C-replete group only; a weak positive correlation was observed between sE-selectin and alpha-tocopherol concentration. In conclusion, alpha-tocopherol supplementation had little effect on cardiovascular disease risk factors in healthy subjects and the effects of tocopherol were not consistently affected by plasma vitamin C concentration.     

Molecular bases of the treatment of Alzheimer's disease with antioxidants: prevention of oxidative stress

Alzheimer's disease is associated with a systemic oxidative stress situation which can be followed in vivo by determining biomarkers such as plasma lipoperoxides and TBARS levels and the oxidation degree of glutathione in red blood cells. It has been observed that Alzheimer's patients show an increased level of plasma TBARS, which indicates a higher free radical oxidation of plasma unsaturated phospholipids, and an increased oxidation of red blood cells glutathione, which indicates oxidative stress in peripheral cells. This latter, glutathione oxidation, was found to correlate statistically with the cognitive status of the patients. Treatment with vitamin E resulted in an improved cognitive performance only of those patients in which the tocopherol acted as an antioxidant, according to blood indicative markers of oxidative stress. Indeed, the effect of vitamin E on Alzheimer's disease patients showed considerable variations both in its antioxidant function and in its capacity to improve cognitive functions. An important conclusion from the reported results is that epidemiological or clinical studies that aim to test the effect of antioxidant supplementation on given functions should include the determination of the antioxidant status of the patients by the measurement of blood markers of oxidative stress.     

Oral supplements of vitamin E improve measures of oxidative stress in plasma and reduce oxidative damage to LDL and erythrocytes in beta-thalassemia intermedia patients

Fifteen beta-thalassemia intermedia patients, not requiring chronic transfusional therapy, were monitored in order to check their antioxidant status, and the lipid oxidation products in plasma, LDL, and erythrocytes before and during a 9-month oral treatment with 600 mg/day vitamin E. The low level of vitamin E, and high level of malondialdehyde in plasma clearly tended to normalize after three months (P < .001), and were quite similar to control after six months. The abnormally low level of vitamin E in LDL and the four times higher than control basal level of conjugated dienes (LDL-CD), were not modified after three months of treatment. Significant changes of LDL-VE (P < .05) and of the basal LDL-CD (P < .001) were evident after six months. LDL-VE was within the normal range after nine months, whereas LDL-CD still appeared twice as higher than control. Plasma vitamin A, ascorbate, beta-carotene, and lycopene increased markedly at the end of the trial (P < .005). The level of vitamin E in red blood cells was normalized after six months of supplementation. A decrease of the baseline value of conjugated dienes was observed after nine months, although it remained 1.4-fold higher than control. The RBC count and hematocrit appeared higher at the end of the trial (P < .05 and P < .001, respectively). The hemoglobin value did not show variations. A shift to normal of the resistance of erythrocytes to osmotic lysis was observed. Our findings provide evidence that an oral treatment with vitamin E improves the antioxidant/oxidant balance in plasma, LDL particles, and red blood cells, and counteracts lipid peroxidation processes in beta-thalassemia intermedia patients.     

Spectrophotometric method for determination of tocopherol in red blood cells

A relatively rapid procedure is described for the spectrophotometric determination of total tocopherol in red blood cells (RBC) based on a modification of the original Emmerie-Engel reaction. The critical feature in this method is the presence of a large amount of an added antioxidant, pyrogallol or ascorbic acid, during the saponification and extraction stages and the use of thin-layer chromatography for tocopherol purification. The total tocopherol levels of plasma and erythrocytes were determined for a number of human subjects, for patients with abetalipoproteinemia, and for rats. It was found that these levels had a wide range in normal human subjects but that the ratio of RBC to plasma tocopherol was relatively constant and equal to 0.18, uncorrected, and 0.21 when both RBC and plasma values were corrected to 100% recovery. The RBC-to-plasma ratio for rats was 0.39. The accuracy of this ratio determined by the spectrophotometric procedure was verified by measuring the distribution of [(14)C]tocopherol in RBC and plasma when radioactive vitamin E was introduced into the blood by both in vitro and in vivo techniques. The addition of radioactive tocopherol to RBC or plasma at the initial stage of the analysis permits an accurate determination of the total tocopherol in RBC or plasma by calculations based on the recovery of the added isotope. This procedure for erythrocyte tocopherol analysis is compared with a gas-liquid chromatographic method in current use.     

Tocopherol mobilization during intensive exercise

This work shows that the level of plasma tocopherol (vitamin E) which has free radical scavenging properties rises significantly during intensive exercise. It is proposed that mobilization of tocopherol could help to prevent lipoperoxidation phenomena occurring in exercising skeletal muscle. A hypothetical mechanism relating to a lipolysis effect is discussed to explain this mobilization.     

Vitamins A and E in digestive cancers

Vitamins A and E, transthyretin (TT) and retinol binding protein (RBP) plasma levels were assayed in 70 patients having a recently diagnosed digestive cancer and in 116 controls. After adjustment for sex and age, vitamin A or RBP and TT were found lowered in digestive cancer but vitamin E was lowered only in esophagus cancer. The relationship of vitamin levels to the relative risk of digestive cancer was calculated by multiple logistic conditional regression. TT level remained the only significant parameter. Since TT levels are strongly influenced by the nutritional status of patients, our results suggest that the decreased blood levels of vitamin A and its carriers observed in digestive cancer are the consequence of nutritional alterations evoked by the disease.     

Biochemical consequences of heritable mutations in the alpha-tocopherol transfer protein

Tocopherol transfer protein (TTP) regulates vitamin E status by facilitating the secretion of tocopherol from liver to circulating lipoproteins. Heritable mutations in the ttpA gene, encoding for TTP, result in ataxia with vitamin E deficiency (AVED) syndrome, typified by low vitamin E levels and a plethora of neurological disorders. The molecular mechanisms by which TTP facilitates tocopherol secretion are presently unknown. We recently showed that vitamin E is taken up by hepatocytes through an endocytic process and that, shortly following uptake, the vitamin is found primarily in lysosomes. We showed further that TTP is localized to late endocytic vesicles and that it facilitates the intracellular trafficking of tocopherol from lysosomes to the plasma membrane. To gain insight into the molecular mechanisms that underlie TTP actions, we studied the physiological impact of three naturally occurring heritable mutations in the ttpA gene (the R59W, R221W, and A120T substitutions). We found that these mutations impair the ability of TTP to facilitate the secretion of vitamin E from cells. Furthermore, the degree of impairment corresponded to the severity of the AVED pathology associated with each mutation. In cells that express mutated TTP proteins, vitamin E did not traffic to the plasma membrane and remained "trapped" in lysosomes. In addition, we observed that substitution mutations that cause the AVED syndrome impart a marked instability on the TTP protein. These observations suggest that the physiological role of TTP is anchored in its ability to direct vitamin E trafficking from the endocytic compartment to transport vesicles that deliver the vitamin to the site of secretion at the plasma membrane.     

Vitamin E supplementation alters HDL-cholesterol concentration and paraoxonase activity in rabbits fed high-cholesterol diet: comparison with probucol

Vitamin E and probucol are well-known antioxidants that prevent cells from the oxidative stress, which is a risk factor of atherosclerosis. Male rabbits were fed either 0.03% vitamin E or 0.05% probucol in a 0.5% high-cholesterol (HC) diet for 8 weeks. Vitamin E and probucol significantly suppressed an increase in plasma total-cholesterol (total-C) and low-density lipoprotein cholesterol compared to HC-control group. However, plasma high-density lipoprotein-cholesterol (HDL-C) and HDL-C/total-C ratio levels and plasma paraoxonase activity were only significantly higher in vitamin E group after 8 weeks. Hepatic ACAT activity was significantly lower in both vitamin E and probucol groups than in HC-control group, while HMG-CoA reductase activity was the highest only in the probucol group. Total fecal sterol content was significantly higher in probucol and vitamin E groups than in the two control groups. Some atherogenic signs were discovered in the aortic fatty streak of HC-control group, yet not in other groups. Hepatic mRNA expressions of apo B-100 and apo C-III were significantly lower in probucol group than in other groups. Vitamin E supplementation was found to alter the plasma HDL-C-related factors; meanwhile, probucol supplementation was very effective in enhancing cholesterol metabolism, except for a negative effect that reduced plasma HDL-C concentration.     

Antioxidants and lipid peroxidation status in the blood of patients with alopecia

The aim of this research was to determine levels in blood of vitamin E, beta-carotene, lipid peroxidation as thiobarbituric-acid reactive substances (TBARS) and reduced glutathione (GSH) and activity of glutathione peroxidase (GSH-Px) in patients with alopecia. Studies were carried out on 37 patients with alopecia and 34 healthy age-matched controls. Red blood cell (RBC) and plasma samples from healthy and patient subjects were taken. Beta-cartotene levels (P<0. 001) in plasma and levels of GSH (P>0.05) and the activity of GSH-Px (P<0.05, P<0.01) in both plasma and RBC samples were significantly lower in patients with alopecia than in controls, whereas TBARS levels in plasma (P<0.05) and RBC (P<0.001) samples were significantly higher in patients with alopecia than in controls. However, vitamin E levels in plasma did not differ statistically. Although being far from conclusive, these results provide some evidence for a potential role of increased lipid peroxidation and decreased antioxidants in alopecia.     

Effects of vitamin E on prostacyclin release and lipid composition of the ischemic rat heart

Free radical-mediated reperfusion injury has been established as an important mechanism leading to post-ischemic reperfusion myocardial damage. The present study was undertaken to determine the protective role of vitamin E, a membrane-bound free-radical scavenger, on ischemia-reperfusion myocardial injury. After 4 months of feeding a semipurified diet containing 0, 30, and 3000 ppm of R,R,R,-alpha-tocopherol acetate, rat hearts were subjected to Langendorff perfusion. Myocardial damage was judged by the release of creatine phosphokinase (CPK) after 45 min of global ischemia followed by 20 min of reperfusion. Effluent CPK was significantly lowered in the two tocopherol-supplemented groups, although increasing dietary vitamin E by 100-fold above requirement did not confer further protection. However, effluent prostacyclin, detected as the stable metabolite 6-keto-PGF1 alpha by radioimmunoassay, was potentiated by dietary vitamin E in a dose-dependent manner. Analysis of lipids in cardiac subcellular fractions showed considerable enrichment of tocopherol in these membranes by diets, but the levels of polyunsaturated fatty acids, phospholipids, and cholesterol were essentially unchanged by dietary treatment or ischemia-reperfusion. These data demonstrated that requirement level of tocopherol (30 ppm) in the diet is sufficient to protect against reperfusion injury of the myocardium and suggests that tocopherol is important in maintaining cardiac prostacyclin synthesis under conditions of oxygen stress.