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Title: Variations in the distribution of selenium between erythrocyte glutathione peroxidase and hemoglobin in different human populations

Abstract

The majority of erythrocyte (RBC) selenium (Se) is associated with glutathione peroxidase (GPx) in animals, but most of it is with hemoglobin (Hb) in human RBCs. Dietary forms of Se may influence this distribution since a rat study showed that selenite promoted the deposition of Se in GPx but selenomethionine (SeMet) resulted in greater amounts with Hb. Three different populations of people were chosen to investigate some possible reasons for the Se distribution in human RBC proteins. An average of 12% of the RBC Se (0.71 ng Se/mg Hb) was associated with GPx in people living in Oregon, but nearly 30% of the Se was associated with GPx in RBC (0.26 ng Se/mg Hb) from New Zealanders. Georgia residents with low RBC Se levels (0.35 ng Se/mg Hb) had 38% of the Se associated with GPx as compared to 29% for those with higher RBC levels (0.56 ng Se/mg Hb). In a third group of people the amount of Se tended to be higher in RBC GPx from non-vegetarian OSU students than from vegetarians. The predominant form of Se in meat appears to be selenocysteine, which is metabolized similarly to selenite, and presumably contributes to this difference since many plantmore » foods contain Se as SeMet. These are examples of many possible factors affecting the relative distribution of Se in human RBC proteins.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Oregon State Univ., Corvallis
OSTI Identifier:
5392744
Alternate Identifier(s):
OSTI ID: 5392744
Report Number(s):
CONF-8604222-
Journal ID: CODEN: FEPRA
Resource Type:
Conference
Resource Relation:
Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States); Journal Volume: 45:3; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; SELENIUM; METABOLISM; TISSUE DISTRIBUTION; ERYTHROCYTES; FOOD; GEORGIA; HEMOGLOBIN; MAN; NEW ZEALAND; OREGON; PEROXIDASES; ANIMALS; AUSTRALASIA; BIOLOGICAL MATERIALS; BLOOD; BLOOD CELLS; BODY FLUIDS; CARBOXYLIC ACIDS; DISTRIBUTION; ELEMENTS; ENZYMES; FEDERAL REGION IV; FEDERAL REGION X; GLOBIN; HETEROCYCLIC ACIDS; HETEROCYCLIC COMPOUNDS; MAMMALS; MATERIALS; NORTH AMERICA; ORGANIC ACIDS; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; OXIDOREDUCTASES; PIGMENTS; PORPHYRINS; PRIMATES; PROTEINS; SEMIMETALS; USA; VERTEBRATES 550500* -- Metabolism

Citation Formats

Whanger, P.D., Robinson, M.F., Feldman, E.B., Beilstein, M.A., and Butler, J.A. Variations in the distribution of selenium between erythrocyte glutathione peroxidase and hemoglobin in different human populations. United States: N. p., 1986. Web.
Whanger, P.D., Robinson, M.F., Feldman, E.B., Beilstein, M.A., & Butler, J.A. Variations in the distribution of selenium between erythrocyte glutathione peroxidase and hemoglobin in different human populations. United States.
Whanger, P.D., Robinson, M.F., Feldman, E.B., Beilstein, M.A., and Butler, J.A. Sat . "Variations in the distribution of selenium between erythrocyte glutathione peroxidase and hemoglobin in different human populations". United States. doi:.
@article{osti_5392744,
title = {Variations in the distribution of selenium between erythrocyte glutathione peroxidase and hemoglobin in different human populations},
author = {Whanger, P.D. and Robinson, M.F. and Feldman, E.B. and Beilstein, M.A. and Butler, J.A.},
abstractNote = {The majority of erythrocyte (RBC) selenium (Se) is associated with glutathione peroxidase (GPx) in animals, but most of it is with hemoglobin (Hb) in human RBCs. Dietary forms of Se may influence this distribution since a rat study showed that selenite promoted the deposition of Se in GPx but selenomethionine (SeMet) resulted in greater amounts with Hb. Three different populations of people were chosen to investigate some possible reasons for the Se distribution in human RBC proteins. An average of 12% of the RBC Se (0.71 ng Se/mg Hb) was associated with GPx in people living in Oregon, but nearly 30% of the Se was associated with GPx in RBC (0.26 ng Se/mg Hb) from New Zealanders. Georgia residents with low RBC Se levels (0.35 ng Se/mg Hb) had 38% of the Se associated with GPx as compared to 29% for those with higher RBC levels (0.56 ng Se/mg Hb). In a third group of people the amount of Se tended to be higher in RBC GPx from non-vegetarian OSU students than from vegetarians. The predominant form of Se in meat appears to be selenocysteine, which is metabolized similarly to selenite, and presumably contributes to this difference since many plant foods contain Se as SeMet. These are examples of many possible factors affecting the relative distribution of Se in human RBC proteins.},
doi = {},
journal = {Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)},
number = ,
volume = 45:3,
place = {United States},
year = {Sat Mar 01 00:00:00 EST 1986},
month = {Sat Mar 01 00:00:00 EST 1986}
}

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  • A chromatographic method was developed to determine the distribution of selenium between selenoprotein P, glutathione peroxidase (GSH-Px) and albumin, using two small columns of heparin-Sepharose CL-6B (white) and Reactive Blue 2-Sepharose CL-6B (blue) linked together in tandem. One ml of plasma was diluted to 10 ml with 0.02 M sodium phosphate buffer, pH 7.0, the equilibration buffer, and applied to the white column. This was eluted at flow rate of 30 ml per hour. GSHp-Px was not retained by either column but selenoprotein P was retained by the white column and albumin by the blue column. After the two columnsmore » were separated, selenoprotein P was eluted for 90 min from the white column with a solution containing 500 units of heparin per ml. The albumin was eluted for 55 min from the blue column with 1.4 M NaCl. This method indicated that over 50% of the selenium in plasma from rats, monkeys, humans and sheep was with selenoprotein P, even during deficiency. From 15 to 22% of the selenium was associated with GSH-Px. The percentage of selenium with albumin was dependent upon the selenomethionine content of the diet.« less
  • The effects of different protein and selenium levels on glutathione peroxidase activity in whole blood as a measure of selenium utilization by mice was investigated. 72, 21-day old, male mice (NIH Swiss) were fed rations containing 3 different levels of protein (10%, 15%, 25%) and 3 different levels of selenium (0.003 ppm, 0.2 ppm, 2 ppm) in all possible combinations according to a 3 x 3 factorial design. On the last day of the 3-week experiment, mice were sacrificed and blood was drawn. Glutathione peroxidase activity in whole blood was measured by a modification of the method of Paglia andmore » Valentine (1967). Mean whole blood glutathione peroxidase activities and dietary protein level were negatively correlated in the mice receiving low selenium rations. In moderate and high selenium fed groups, highest glutathione peroxidase activities were found at the moderate protein level (15% of ration) and tended to be lower when either the low protein ration (10%) or high protein ration (25%) was fed. Glutathione peroxidase activities in both the moderate and high selenium fed animals were higher than were those of low selenium fed animals regardless of level of protein.« less
  • GSH-Px activity was determined in the retina of 15 preterm human neonates with gestational ages of 17-28 weeks and birth weights of 120 to 960 g. GSH-Px activity was measured using the coupled assay. The infants survived from 0.5 to 9 hours after parturition. The retinas were removed within 3 hours of autopsy. Through electronmicroscopy, there was verification that the entire retina was removed and no contamination of other eye tissues occurred. After removal, the retinas were immediately dissolved in phosphate buffered pH 7.0 saline for assay of GSH-Px activity. The mean GSH-Px activity was 19.44 +/- 6.44 with amore » range of 11.1 to 32.8 units NAPH/sub 2/ oxidized/min/g protein. There was a negative correlation between birth weight and GSH-Px activity (r = -0.86) and between week of gestation and GSH-Px activity (r = -0.91). The neonatal retina GSH-Px activity was 2 to 15 times higher than found in adult retinas. Thus, this research demonstrates that selenium dependent GSH-Px activity is elevated in the preterm neonate's retina which indicates that retina GSH-Px activity may be an important antioxidation system in the premature neonate.« less
  • Studies were conducted in an attempt to define a biochemical index of selenium toxicity rather than weight loss, liver disease and death. Rats, maintained on selenium deficient diets, received in drinking water various levels of selenium as Na/sub 2/SeO/sub 3/(0.1, 1.0, 1.5, 2.0 ppM). Changes in selenium dependent glutathione peroxidase (GSH-Px) activities and specific activities (nCi/sup 75/ Se/..mu..g Se) were determined in liver, kidney and plasma at baseline and two and ten weeks after repletion. In initial selenium deficient rats, GSH-Px activities were markedly depressed and specific activities elevated as compared to 0.1 ppM controls. After two weeks, liver andmore » plasma GSH-Px activities increased, and plasma, liver and kidney specific activities decreased in a concentration dependent manner. In kidney, there were no differences in enzyme activity at either two or ten weeks. At ten weeks, liver GSH-Px activities continued to increase in the 1.0 ppM group, but were depressed at both the 1.5 and 2.0 ppM levels. Specific activities were also depressed in liver and excretion was not increased at these levels. This suggests a biochemical toxicity in liver at levels above 1.0 ppM after ten weeks, prior to the onset of gross pathological changes.« less
  • Glutathione peroxidase (GPX) is an indicator of Se status, but the regulation of GPX is not understood. Se deficiency decreases GPX activity and mRNA levels in rat liver, but the effect of Se status on GPX mRNA levels in other tissues has not been investigated. To study this regulation, male weanling rats were fed Se-deficient, Se-adequate or high-Se diets. At 35 d, liver, kidney, heart, lung, muscle and testes GPX activities were assayed. mRNA levels were determined by northern blotting using a {sup 32}P-labeled 0.7 kb EcoRI fragment of cloned GPX. In Se-adequate rats, GPX enzyme activity was highest inmore » liver and missing in testis; the ranking was L{much gt}K{gt}Lg{ge}H{gt}M{much gt}T. GPX mRNA level was also highest in liver and missing in testis; the ranking was L{much gt}K{gt}H{gt}Lg{ge}M{much gt}T. Se deficiency decreased the GPX mRNA level dramatically in liver, kidney and heart, and reduced it in lung and muscle, but high Se did not raise GPX mRNA levels above Se-adequate levels. These results show that GPX activity differences are due to different levels of GPX mRNA. The reduction of GPX mRNA levels by Se deficiency demonstrates that low Se status down-regulates GPX mRNA in other tissues as well as liver; high-Se status does not up-regulate GPX mRNA above Se-adequate levels. The tissue-to-tissue variation in GPX mRNA level indicates that other factors in addition to Se status regulate GPX expression.« less