AGE-RELATED-CHANGES OF PLASMA GLUTATHIONE AND CYSTEINE IN BROILERS - EFFECT OF DITHIOTHREITOL REDUCTION IN-VITRO ON FREE AND BOUND POOLS

A study was conducted to determine free and protein-bound pools of glu tathione and cysteine in the plasma of male broiler chicks. Birds were brooded in battery cages and provided ad libitum access to a starter diet and water. Plasma was treated with a reducing agent, dithiothreit ol (DTT), or left untreated, and analyzed by HPLC to determine free an d protein bound pools of reduced (GSH) and oxidized (GSSG) glutathione , cysteine (Cys), and cystine (Cyss). With respect to total plasma poo ls of GSH and Cys, be between 0 and 21 d of age; 1) free GSH increased from 30 to 90% with a reciprocal decrease in protein-bound GSH, but C SSG was not detected; and 2) free Cys decreased from 20 to 10%, free C yss increased from 24 to 45%, and protein-bound Cys decreased from 55 to 44%. The majority of the GSH plasma pool in this study was present in a free, acid-soluble form, whereas most of the total Cys pool was p resent as Cyss or bound to protein.