Effects of vitamin A deficiency on mitochondrial function in rat liver and heart

The aim of this study was to investigate comparative effects of vitamin A deficiency on respiratory activity and structural integrity in liver and heart mitochondria. Male rats were fed a liquid control diet (control rats) or a liquid vitamin A-deficient diet (vitamin A-deficient rats) for 50 days. One group of vitamin-A deficient rats was refed a control diet for 15 days (vitamin A-recovered rats). To assess the respiratory function of mitochondria the contents of coenzyme Q (ubiquinone, CoQ), cytochrome c and the activities of the whole electron transport chain and of each of its respiratory complexes were evaluated. Chronic vitamin A deficiency promoted a significant increase in the endogenous coenzyme Q content in liver and heart mitochondria when compared with control values. Vitamin A deficiency induced a decrease in the activity of complex I (NADH-CoQ reductase) and complex II (succinate-CoQ reductase) and in the levels of complex I and cytochrome c in heart mitochondria. However, NADH and succinate oxidation rates were maintained at the control levels due to an increase in the CoQ content in accordance with the kinetic behaviour of CoQ as an homogeneous pool. On the contrary, the high CoQ content did not affect the electron-transfer rate in liver mitochondria, whose integrity was preserved from the deleterious effects of the vitamin A deficiency. Ultrastructural assessment of liver and heart showed that vitamin A deficiency did not induce appreciable alterations in the morphology of their mitochondria. After refeeding the control diet, serum retinol, liver and heart CoQ content and the activity of complex I and complex II in heart mitochondria returned to normality. However, the activities of both whole electron transfer chain and complex I in liver were increased over the control values. The interrelationships between physiological antioxidants in biological membranes and the beneficial effects of their administration in mitochondrial diseases are discussed.     

Effects of semistarvation on rat liver, kidney, and heart mitochondrial function.

Two groups of rats were provided simultaneously with a commercial stock diet for a period of 7 days. One group was fed ad libitum (control), and the other was restricted to one-fourth of the daily intake of control animals (semistarved). Body weight declined significantly in semistarved rats whereas body weight of controls increased over the 7-day period. The following were determined in vitro on mitochondria isolated from liver, kidney, and heart tissues of both groups: substrate-stimulated and DNP-uncoupled respiratory rates; specific acivities of the Krebs cycle dehydrogenases, and cytochrome c oxidase. Degradative effects of reduced food intake on mitochondrial function were observed. Uncoupled respiratory rates of liver and kidney mitochondria (using succinate as substrate) and heart mitochondria (using alpha-ketoglutarate and pyruvate) were lower. Also lower were activities of isocitrate dehydrogenase, NADP: isocitrate dehydrogenases, transhydrogenase, succinate dehydrogenase, and cytochrome c oxidase of heart mitochondria, transhdrogenase of liver mitochondria, and isocitrate dehydrogenase and transhydrogenase of kidney mitochondria. Such decreases in enzyme activities under conditions of dietary protein deficiency might have their basis in breakdown rates exceeding synthesis rates or result from partial inactivation of existing enzyme protein. Thus, there is evidence that responses to semistarvation of such parameters of mitochondrial function may differ among various tissues. In addition, liver and kidney citrate levels were lower and heart citrate level higher with semistarvation.     

Changes in activity of the Cu-Zn superoxide dismutase enzyme in tissues of the rat with changes in dietary copper.

The effects of dietary copper level on tissue activities of the copper containing superoxide dismutase (CuSOD) were investigated, and these activities related to those of other copper containing enzymes particularly cytochrome oxidase. Male weaning rats were fed a basal diet (containing 0.8 mg Cu/kg) or this diet supplemented with 4 or 24 mg Cu/kg. After 6 weeks, rats fed the basal diet were then repleted using the high copper diet. In the two copper supplemented groups, no differences were observed in any of the parameters measured. In these groups, tissue activities of CuSOD were in the order of liver greater than kidney greater than RBC greater than testis greater than heart greater than brain greater than lung greater than muscle. In the basal group, CuSOD activity decreased in liver; RBC and heart to 14, 25, and 61%, respectively, of control activities after 6 weeks' depletion; tissues other than brain or muscle showed smaller but significant changes. Conversely, heart and muscle cytochrome oxidase activities decreased to 30 and 45% of control activity and liver to 70%. With repletion, CuSOD activities in liver and heart increased more rapidly than did cytochrome oxidase activities. It is concluded that liver CuSOD activity, which is normally high, is greatly reduced with little change in cytochrome oxidase activity; the reverse is found for heart and muscle tissue. The relevance of these changes to the maintenance of tissue integrity is discussed.     

Content and Redistribution of Vitamin E in Tissues of Wistar Rats Under Oxidative Stress Induced by Hydrazine

Hydrazine toxicity is associated with generation of several kinds of free radicals and oxidative stress in cell. Experiments in vivo have demonstrated that oxidative stress could either diminish or increase concentration of vitamin E in some tissues. Thus in the present study we performed experiments to determine whether hydrazine-induced oxidative stress would change the tissue levels of the vitamin. Seven days of hydrazine intoxication led to accumulation of different amounts of vitamin E: 215% in the liver, 118% in the heart, 135% in the spleen, and 100% in the muscle over control value. There were no changes in the level of the vitamin in kidney and pancreas, despite its significant depletion in the serum. In tissue that accumulated vitamin E after hydrazine treatment, an increased of oxidative stress measured by the concentration of lipid-soluble fluorophore was observed. Significant increases of 107%, 46%, 72%, and 58% over control values were observed in the liver, heart, spleen, and muscle, respectively. Rats treated with hydrazine and pharmacological doses of alpha-tocopherol accumulated higher concentrations of vitamin E in all studied tissues compared with the alpha-tocopherol-only treated rats. However, in tissues with elevated levels of fluorophore as liver, heart, spleen, and muscle, the accumulation of vitamin E was 5.03, 4.5, 4.03, and 4.6 times higher than in alpha-tocopherol-treated rats, respectively. Vitamin E concentration was much higher than in kidney and pancreas, where the accumulation was only 2.31 and 2.6 times higher. On the other hand, 3 days of hydrazine treatment did not change either the level of lipid-soluble fluorophore or the level of vitamin E in the liver mitochondria, microsomes, and homogenate. In skeletal muscle vitamin E caused decreased lipofuscin accumulation, and in pancreas vitamin E increased lipofuscin accumulation. Our data indicate that hydrazine is able to modify significantly vitamin E status in different rat tissues.     

Coenzyme Q intake elevates the mitochondrial and tissue levels of Coenzyme Q and alpha-tocopherol in young mice

The main objective of this study was to resolve the issue of whether the amounts of Coenzyme Q (CoQ), which is endogenously synthesized in cells, can be elevated in tissues and mitochondria of young mice by dietary supplementation with CoQ10. The prevalent view is that the uptake of exogenous CoQ by tissues other than plasma and liver either does not occur or is quite minimal. Mice, 6 mo of age, were fed 0, 148 or 654 mg CoQ10/(kg body x d) in their diets for 11 wk. CoQ10 intake enhanced both CoQ9 and CoQ10 homologues in the plasma, and in homogenates and mitochondria of liver, heart and skeletal muscle. CoQ was elevated in brain mitochondria, but not in the brain homogenate. The uptake of exogenous CoQ was higher in mitochondria of heart and skeletal muscle than those in liver. CoQ10 administration also elevated the alpha-tocopherol concentration in tissue homogenates and their mitochondria, thereby providing an in vivo indication of the "sparing" effect of CoQ on alpha-tocopherol. Results of this study demonstrate that, contrary to the historical view, both total and mitochondrial CoQ concentrations in the heart and skeletal muscle and in the mitochondria of brain of young mice can be augmented by dietary supplementation. Furthermore, CoQ intake enhances the antioxidative potential of tissues by elevating the endogenous amounts of alpha-tocopherol.     

Effects of vitamin E deficiency on the activities of lipid-requiring enzymes in rabbit liver and muscle.

The effects of vitamin E deficiency on membrane integrity were studied by examining the temperature dependence of membrane-bound enzyme activities in liver mitochondria and microsome and in muscle sarcoplasmic reticulum. In vitamin E-deficient rabbits, the specific activities at 37 degrees of mitochondrial oligomycin-sensitive ATPase (EC 3.6.1.3), beta-hydroxybutyrate dehydrogenase (EC 1.1.1.30), and microsomal glucose-6-phosphatase (EC 3.1.3.9) were increased, whereas those of microsomal NADH cytochrome C reductase (EC 1.6.99.3) and sarcoplasmic reticulum Ca-ATPase were reduced in comparison to control rabbits. Arrhenius plots of activity against temperature yielded a linear plot over the range 10 to 40 degrees in the case of beta-hydroxybutyrate dehydrogenase, NADH cytochrome C reductase and Ca-ATPase, and multiple discontinuities for glucose-6-phosphatase and oligomycin-sensitive ATPase. In control rabbits, all five enzymes showed a single discontinuity in the Arrhenius plot over the range 16 to 19 degrees. These results reflect changes in the microenvironment of membrane-bound enzymes as a consequence of vitamin E depletion.     

Subcellular distribution of branched-chain aminotransferase activity in rat tissues

The activity of branched-chain aminotransferase in mitochondria isolated from rat tissues was examined, and the mitochondrial contribution to total tissue branched-chain aminotransferase activity was calculated using the mitochondrial marker enzyme citrate synthase. Mitochondrial aminotransferase activity was highest in heart followed by skeletal muscle, kidney and brain. In heart muscle all of the aminotransferase activity was accounted for by the mitochondrial fraction. Activity was found to be mitochondrial in skeletal muscle with high red fiber content and also in kidney cortex. Activity was predominantly cytosolic in brain and muscles with high white fiber composition. Thus, the distribution of branched-chain aminotransferase activity in skeletal muscle was dependent on fiber type. No branched-chain aminotransferase activity was detected in liver mitochondria, and in liver tissue activity was too low to be relevant at physiological concentrations of branched-chain amino acids. Within a tissue, regardless of the subcellular distribution of aminotransferase activity, the relative rates of transamination with subsaturating or "saturating" concentrations of KIV or isoleucine were similar. Finally, amino acid preference was also similar within a tissue, but not necessarily between or among different tissues.     

Increased heme oxygenase-1 expression during copper deficiency in rats results from increased mitochondrial generation of hydrogen peroxide

The activity of hepatic heme oxygenase (HO) in rats is elevated in response to copper deficiency. However, the mechanism responsible for the increase in HO activity is poorly understood. Oxidative stress is a common denominator for many of the signals that induce HO-1, the inducible isoform of HO. The present study evaluated the role of H(2)O(2) and the mitochondrial electron transport chain as a potential mechanism for the induction of HO-1 during copper deficiency. Mitochondria isolated from the livers of young male rats fed a copper-deficient diet for 5 wk had significantly (P < 0.05) reduced levels of NADH:cytochrome c reductase (31% reduction), succinate:cytrochrome c reductase (42% reduction), and cytochrome c oxidase (70% reduction) activities and significantly increased production of H(2)O(2) (48% increase) when glutamate was used as a substrate. Hepatic levels of HO-1 protein and mRNA were also significantly elevated (48 and 20%, respectively) in copper-deficient rats, indicating that copper deficiency stimulated the expression of the HO-1 gene. Furthermore, hepatic HO-1 protein content was best described by a regression model that included mitochondrial NADH:cytochrome c reductase and succinate:cytochrome c reductase activities, but not cytochrome c oxidase activity (R(2) = 0.54, P < 0.02). Hydrogen peroxide is a known inducer of HO-1, and our results suggest that increased mitochondrial H(2)O(2) production resulting from inhibition of respiratory complex activities contributes to the induction of HO-1 during copper deficiency. The levels of HO-1 protein and mRNA were also elevated (85 and 95%, respectively) in hearts from copper-deficient rats, indicating that the effects of copper deficiency on HO-1 gene expression are not limited to hepatic tissue.     

Biochemical and pathological changes in tissues of Friesian cattle during the experimental induction of copper deficiency.

1. Copper deficiency was induced in five Friesian cattle offered a semi-synthetic diet containing less than 1 mgCu/kg. Changes in blood and liver Cu contents and in the Cu-containing enzymes, ferroxidase I (caeruloplasmin; EC 1.16.3.1) and monoamine oxidase (EC 1.4.3.4) of plasma and cytochrome oxidase (EC 1.9.3.1) of liver and skeletal muscle were monitored during Cu depletion. 2. Rapid decreases in blood and liver Cu and plasma ferroxidase I activity were found at least 80 d before the first appearance of overt clinical signs of deficiency. Plasma monoamine oxidase and liver cytochrome oxidase activities decreased less rapidly and thus may provide useful indices of chronic Cu depletion.     

Lipid peroxidation as a mechanism of alcoholic liver injury: role of iron mobilization and microsomal induction

Lipid peroxidation has been invoked as a mechanism of alcoholic liver injury but its role has been controversial and the mechanism by which it occurs is unclear. Catalytic iron is known to play an important role in cellular injury and is produced during mobilization of ferritin iron. In vivo administration of a large acute dose of ethanol (5 g/kg) which produces hepatic lipid peroxidation in chow-fed rats resulted in mobilization of non-heme iron. The generation of NADH from alcohol metabolism via ADH or superoxide from acetaldehyde-xanthine oxidase mobilized iron from horse spleen ferritin in vitro. Chronic feeding of alcohol as 36% of energy for 6 weeks does not itself produce peroxidation in the rat but potentiates acute effects of ethanol. It produced microsomal induction which enhanced iron-stimulated lipid peroxidation and increased hepatic non-heme iron. Carbon monoxide increased rather than decreased accumulation of microsomal peroxidation products in vitro suggesting that cytochrome P-450 reductase mediates peroxidation but cytochrome P-450 may metabolize products. Incubation at lowered oxygen tensions equivalent to those observed in the perivenular zone (pO2 = 24 mmHg) enhanced in vitro iron mobilization but decreased peroxidation. Lipid peroxidation and its stimulation by iron mobilization and microsomal induction may be an important contributory mechanism of alcohol-induced liver injury.     

Effects of dietary vitamin E and high level of ascorbic acid on iron distribution in rat tissues

The effects of dietary vitamin E and high-level supplementation of ascorbic acid on iron distribution in rat tissues were studied. Weanling male Sprague-Dawley rats, fed ad libitum a vitamin E and ascorbic acid free basal diet, were divided into four groups. They were supplemented with 0 or 45 IU/kg diet of vitamin E, and O or 0.2% ascorbic acid in a 2 X 2 complete factorial design. After 12 weeks, rats were killed; blood, liver, spleen, heart and skeletal muscle were collected for analysis. Vitamin E deficiency resulted in significantly decreased plasma iron levels and total iron binding capacity. The total iron and nonheme iron contents of the liver and spleen were significantly higher in the vitamin E-deficient groups compared with control groups. Vitamin E or ascorbic acid supplementation had no effect on iron content of the heart. Non-heme iron levels on per gram tissue were highest in the skeletal muscle of the group to which no vitamin E or ascorbic acid were supplemented. It appears that vitamin E and ascorbic acid interactively affect the iron distribution in rat tissues.     

Cytochrome b5/cytochrome b5 reductase complex in rat liver microsomes has NADH-linked aquacobalamin reductase activity.

To study the mammalian system for synthesis of cobalamin coenzymes, rat liver microsomal NADH-linked aquacobalamin reductase was characterized. Microsomal NADH-linked aquacobalamin reductase, which was solubilized with 10 g/L sodium deoxycholate, showed identical elution behavior to NADH-cytochrome c reductase (cytochrome b5/cytochrome b5 reductase complex) on DEAE-Toyopearl 650 column chromatography. By mixing the purified cytochrome b5 with cytochrome b5 reductase, cob(II)alamin was immediately formed from aquacobalamin and NADH. These results provide evidence that the NADH-linked aquacobalamin reductase activity is derived from the cytochrome b5/cytochrome b5 reductase complex in rat liver microsomes. Some properties of the cytochrome b5/cytochrome b5 reductase complex in the form of NADH-linked aquacobalamin reductase were studied. The inhibition studies with cobalamin analogues suggested that hydrophobicity of the corrin ring of cobalamin molecule is involved in binding of cobalamin to the cytochrome b5/cytochrome b5 reductase complex.     

Glutathione turnover is increased during the acute phase of sepsis in rats

Glutathione metabolism during infection has been poorly documented. Glutathione concentrations and synthesis rates were studied in infected rats (2 d after infection) and in pair-fed controls. Glutathione synthesis rates were determined in liver, spleen, lung, small and large intestine, skeletal muscle, heart and blood by a 4-h or 6-h (15)N cysteine infusion. The activities of four hepatic enzymes involved in glutathione metabolism were also determined. Glutathione synthesis rates were significantly greater in liver (+465%), spleen (+388%), large intestine (+109%), lung (+100%), muscle (+91%) and heart (+80%) of infected rats compared with pair-fed controls. Glutathione concentrations were also greater in these tissues but were unaffected in small intestine and lower in blood. In keeping with the stimulation of liver glutathione synthesis, the activities of liver gamma-glutamyl-cysteine synthetase and glutathione reductase were significantly greater in liver of infected rats than of pair-fed rats. From the present study, we estimate that glutathione synthesis accounts for at least 40% of the enhanced cysteine utilization during infection. This increased utilization may be the primary cause of an enhanced cysteine requirement in infection.     

Different variations of tissue B-group vitamin concentrations in short- and long-term starved rats

Prolonged starvation changes energy metabolism; therefore, the metabolic response to starvation is divided into three phases according to changes in glucose, lipid and protein utilisation. B-group vitamins are involved in energy metabolism via metabolism of carbohydrates, fatty acids and amino acids. To determine how changes in energy metabolism alter B-group vitamin concentrations during starvation, we measured the concentration of eight kinds of B-group vitamins daily in rat blood, urine and in nine tissues including cerebrum, heart, lung, stomach, kidney, liver, spleen, testis and skeletal muscle during 8?d of starvation. Vitamin B1, vitamin B6, pantothenic acid, folate and biotin concentrations in the blood reduced after 6 or 8?d of starvation, and other vitamins did not change. Urinary excretion was decreased during starvation for all B-group vitamins except pantothenic acid and biotin. Less variation in B-group vitamin concentrations was found in the cerebrum and spleen. Concentrations of vitamin B1, vitamin B6, nicotinamide and pantothenic acid increased in the liver. The skeletal muscle and stomach showed reduced concentrations of five vitamins including vitamin B1, vitamin B2, vitamin B6, pantothenic acid and folate. Concentrations of two or three vitamins decreased in the kidney, testis and heart, and these changes showed different patterns in each tissue and for each vitamin. The concentration of pantothenic acid rapidly decreased in the heart, stomach, kidney and testis, whereas concentrations of nicotinamide were stable in all tissues except the liver. Different variations in B-group vitamin concentrations in the tissues of starved rats were found. The present findings will lead to a suitable supplementation of vitamins for the prevention of the re-feeding syndrome.     

不同训练方式与大鼠骨骼肌线粒体通透性转换孔及细胞凋亡

目的比较不同训练方式对大鼠骨骼肌线粒体通透性转换孔(MPTP)及细胞凋亡的影响。方法以大鼠游泳训练和一次性力竭游泳为运动模型,将24只SD大鼠随机分为对照组(C)、游泳训练组(T)和一次性游泳力竭组(E)。T组大鼠进行无负重游泳训练6周,每周6次,1～2周每次训练45min,3～4周每次60min,5～6周为90min,末次训练24h后取股四头肌;E组正常饲养6周后于一次性力竭游泳后即刻取股四头肌。用紫外分光光度仪检测MPTP的开放;RT-PCR检测Bcl-2和Bax mRNA的表达;western blot检测细胞色素c(Cytc)的释放。结果①游泳训练没有导致大鼠骨骼肌MPTP的开放发生显著性变化,Bcl-2mRNA表达明显增强,Bax mRNA的表达及Cytc的释放量显著减少。②一次性力竭游泳导致大鼠骨骼肌MPTP的开放程度显著增大,Bcl-2mRNA表达显著降低,Bax mRNA表达和Cytc释放量显著增加。结论不同训练方式会通过调节骨骼肌线粒体通透性转换孔的开放及凋亡蛋白的释放来调节细胞凋亡。     

Proteomics analysis of apoptosis-regulating proteins in tissues with different radiosensitivity

The aim of this study was to identify of radiosusceptibility proteins in tissues with different radiosensitivity. C3H/HeJ mice were exposed to 10 Gy. The tissues were processed for proteins extraction and were analyzed by 2-dimensional electrophoresis. The proteins were identified by matrix-assisted laser desorption ionizing time-of-flight mass spectrometry and validated by immunohistochemical staining and Western blotting. The peaks of apoptosis levels were 35.3 +/- 1.7% and 0.6 +/- 0.2% in the spleen and the liver, respectively, after ionizing radiation. Analysis of liver tissue showed that the expression level of ROS related proteins such as cytochrome c, glutathione S transferase, NADH dehydrogenase and peroxiredoxin VI increased after radiation. The expression level of cytochrome c increased to 3-fold after ionizing radiation in both tissues. However in spleen tissue, the expression level of various kinds of apoptosis regulating proteins increased after radiation. These involved iodothyronine, CD 59A glycoprotein precursor, fas antigen and tumor necrosis factor -inducible protein TSG-6n precursor after radiation. The difference in the apoptosis index between the liver and spleen tissues is closely associated with the expression of various kinds of apoptosis-related proteins. The result suggests that the expression of apoptosis-related protein and redox proteins play important roles in this radiosusceptibility.     

Effect of naphthalene on respiration in heart mitochondria and intact cultured cells

Mitochondrial respiration is inhibited 50% by 10 ppm (78 μm) naphthalene. NADH oxidase, NADH-cytochrome c reductase, ubiquinone-50 oxidase, and NADH-ubiquinone reductase are inhibited, while succinate oxidations, NADH-ferricyanide reductase, NADH-indophenol reductase, and ATPase activities are not inhibited. The $\text{ADP}\text{O}$ ratio of coupled mitochondria is not decreased. Inhibition of respiration occurs at the level of coenzyme Q. Oxygen consumption of intact cultured cells is also inhibited by naphthalene as in isolated mitochondria. Exposure to naphthalene at concentrations greater than 7.5 ppm causes cultured cells to round up and release from the flask surface, with eventual death the result. The effects of naphthalene on morphology and respiration are very similar, suggesting that mitochondrial inhibition plays a significant role in effects of naphthalene on intact cells.     

The effect of long-term fasting on the branched chain acylcarnitines and branched chain carnitine acyltransferases.

The effect of fasting for 8 days on the levels of carnitine acyltransferases in heart, liver, liver mitochondria, skeletal muscle, skeletal muscle mitochondria, kidney, and testes in young adult male rats was determined. The specific activities of acetyl-, octanyl-, isobutyryl-, and isovaleryl-carnitine acyltransferase in mitochondria isolated from the livers of fasted animals were significantly higher than the levels of the transferases isolated from livers of fed animals. Similar results were obtained with the 500 x g supernatant fluids from liver. In contrast, the specific activities of carnitine acyltransferases of 500 x g supernatant fractions isolated from heart, skeletal muscle, kidney, and testes were the same for fed as fasted animals. The total carnitine content of liver, muscle, heart, and kidney was less in animals fasted for 8 days than in fed animals, but the amount/g of organ was higher in the animals fasted for 8 days. The amount of specific short-chain acylcarnitines in liver, muscle, and heart was determined for both fed and fasted animals. The amount of isobutyrylcarnitine and isovalerylcarnitine increased significantly in muscle from fasted animals. These data are consistent with the previous suggestion that carnitine may have a role in the metabolism of the branched-chain amino acids.     

Mitochondrial function in rats is affected by modification of membrane phospholipids with dietary sardine oil

Phospholipids of heart and liver of rats fed a diet containing sardine oil had more omega 3 polyunsaturated fatty acids and less omega 6 polyunsaturated fatty acids than those of rats fed corn oil, whereas there was little difference in the fatty acid composition of brain phospholipids. The mass of phospholipid classes in rat heart mitochondria was not changed, but their fatty acid compositions were altered. Modification of the fatty acid compositions of mitochondrial phosphatidylcholine and phosphatidylethanolamine reached a plateau after 10 d of feeding, but that of cardiolipin continued for 30 d. The O2 consumption rate of rat heart mitochondria decreased as the fatty acid composition of the phospholipids changed. This may be due to the reduction of the activity of cytochrome c oxidase, which requires cardiolipin for its activity. However, F1F0-ATPase, which also requires cardiolipin, was activated under the same conditions.     

克山病病区粮饲养大鼠~(75)Se代谢的实验观察

以克山病病区和非病区粮饲养大鼠(饲料号为13和35)6—13周进行~(75)Se示踪代谢实验,观察11种组织脏器(褐脂、胸腺、血液、心脏、肺、肌肉、骨、肾、脾、肝、肠)~(75)Se(Na_2SeO_3)的吸收量和体内分布状况。结果表明,自由进食条件下,病区饲料组动物~(75)Se吸收量高于非病饲料组。其中以13号莜麦饲料组差异最为明显(A实验)。对饲条件下病区组动物~(75)Se的吸收量仍高于非病区组。但是差异程度较自由进食组为小(B实验)。各组动物体内不同组织脏器~(75)Se的分布梯度呈现一定规律性。皆以肾脏的吸收量为最高,其次是肝、脾脏及胸腺等,吸收量最低的是肌肉、心脏及骨骼。 在观察的一周之内,随时间的增加,~(75)Se于组织脏器中的含量,病区饲料组与非病区饲料组有不同的动态变化。 病区与非病区组间~(75)Se吸收量规律性差别,反映了病区组动物在病区出产的饲料影响下,体内硒不足或缺乏,表明病区与非病区出产的粮食存在着质的差异,证实了病区水土——食物链因素对动物机体硒代谢有明显影响。