Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2004
Publication Date: 3/7/2005
Citation: Johnson, W.T., Lukaski, H.C. 2005. Serum superoxide dismutase (SOD) activity is an index of copper status [abstract]. The Federation of American Societies for Experimental Biology Journal. 19(5):A1485. Interpretive Summary:
Technical Abstract: The sensitivity and specificity of SOD assays employing xanthine/xanthine oxidase as the superoxide generator can be improved by conducting the assay at pH 10 with acetylated ferricytochrome c (A-cyt c) as the superoxide detector. We tested the hypothesis that SOD activity assayed in serum under these conditions is a sensitive index of Cu status. Serum SOD activity and several indices of Cu status were measured in weanling, Sprague- Dawley rats fed graded levels of Cu in an AIN93G diet for 5 weeks. Dietary Cu Serum SOD mg/kg Units/mL+ male female <1 20±7**a 40±13**a 1 60±21**b 137±20**b* 1.5 94±20**c 137±14**b* 2 95±18**c 148±26**b* 2.5 112±4**c 161±8**b* 3 105±8**c 146±12**b* 6 109±6**c 147±11**b* +A unit of activity equals the amount of SOD that inhibits the reduction of A-cyt c by 50%. a**Values are means±SD. Means in a column not sharing a superscript letter are significantly different. *Females different than males (P<0.05, Tukey's test). Serum SOD activity declined below dietary Cu levels of 1.5 mg/kg in males and 1 mg/kg in females. Furthermore, serum SOD activity was highly correlated with liver Cu in males (R**2=0.94, P<0.0001) and females (R**2=0.88, P<0.0001). In addition, serum SOD, ceruloplasmin, liver cytochrome c oxidase activities and liver Cu concentrations all showed sharp declines when kidney Cu concentration dropped below 16-20 mg/g dry wt. These results indicate that serum SOD activity is a sensitive indicator of Cu status.