ABSTRACT
Plasma-, erythrocyte- and liver Se-dependent glutathione peroxidase (GPx) activity, ascorbic acid (AA) concentration, and erythrocyte and liver Se levels were analyzed in groups of guinea pigs fed a Torula yeast-based semipurified diet supplemented with either O (-AA), 200 (+AA), or 400 (++AA) mg of AA/kg of diet and either 0.05 (+Se) or 0.2 (++Se) ppm of Se for 24 days. Plasma, erythrocyte, and liver AA concentration were directly related to the levels of AA fed. There were 21.2 +/- 2.7% and 51.2 +/- 4.5% (p less than 0.0001) increases in erythrocyte and liver Se, respectively, in ++Se guinea pigs compared to +Se guinea pigs. Dietary AA had no effect on erythrocyte or liver Se levels. Plasma, erythrocyte, and liver GPx specific activities were significantly (p less than 0.001) increased in ++Se guinea pigs compared to +Se guinea pigs. In addition, liver, plasma, and erythrocyte GPx activities were directly related to the level of AA fed. These data indicate that dietary AA has no influence on tissue levels of Se but increases plasma, liver, and erythrocyte GPx activities in the guinea pig.
Subject(s)
Ascorbic Acid/pharmacology , Diet , Selenium/pharmacology , Animals , Ascorbic Acid/metabolism , Erythrocytes/metabolism , Glutathione Peroxidase/metabolism , Guinea Pigs , Liver/metabolism , Male , Selenium/metabolismABSTRACT
An improved method for the measurement of superoxide dismutase (SOD) activity in guinea pig erythrocytes was developed. Alteration of guinea pig erythrocyte superoxide dismutase activity by the dietary antioxidants ascorbic acid and selenium was investigated. Erythrocyte SOD activity was directly related to the ascorbic acid intake of guinea pigs fed 0.05 ppm of selenium. Dietary levels of ascorbic acid were 0, 200 and 400 mg/kg). In guinea pigs fed 0.20 ppm of selenium, there was an increase in superoxide dismutase activity only in the group of animals fed the 400 mg ascorbic acid/kg of diet. Results suggest that substantial protection from deleterious O2-. can be provided by changes in dietary ascorbic acid.
Subject(s)
Antioxidants/pharmacology , Erythrocytes/enzymology , Superoxide Dismutase/blood , Animals , Ascorbic Acid/pharmacology , Diet , Guinea Pigs , Male , Selenium/pharmacologyABSTRACT
14C1-Linolenic acid was incorporated into lipids of hearts, livers, and carcasses of male rats. We studied the influence of diet composition on extent and distribution of radioactivity. A CHOW diet, a purified, essential fatty acid (EFA)-deficient diet, a purified control diet, and EFA-deficient diets with four fatty acid supplements were used. Supplements of 18:2n-6, 20:4n-6, 15:3n-3, and 22:6n-3 were given as single doses. Radioactivities in liver phosphatidyl ethanolamines (PE), phosphatidyl cholines, and neutral lipids were measured. The distribution of radioactivity among the fatty acids in liver phospholipids was determined. Rats on CHOW diet incorporated far less radioactivity than any other group into lipids of hearts and livers. Most of the activity in livers was recovered as 20:5n-3 and 22:6n-3 in all rats. In EFA-deficient rats, the radioactivity in 22:6n-3 of liver PE was still increasing 36 hr after 14C1-linolenic acid had been administered. The n-6 supplements (18:2n-6 and 20:4n-6) seemed to reduce the coversion of 20:4n-3 to 20:5n-3 (desaturation), whereas the n-3 supplements (18:3n-3 and 22:6n-3) reduced the conversion of 20:5n-3 to 22:5n-3 (elongation). Formation of 22:6n-3 may be controlled by 22:6n-3 itself at the elongation of 20:5n-3 to 22:5n-3.
