A METHOD FOR DETERMINATION OF TOTAL GLUTATHIONE AND TOTAL CYSTEINE ASS-CARBOXYMETHYL DERIVATIVES BY USING AN AMINO-ACID ANALYZER, AND ITS APPLICATION TO SAMPLES FROM RAT-LIVER, KIDNEY AND BLOOD AFTER INTRAPERITONEAL ADMINISTRATION OF -GLUCO-TETRAHYDROXYBUTYL)THIAZOLIDINE-4-CARBOXYLIC ACID

The effects of intraperitoneal administration of 2-(4-carboxy-D-gluco- tetrahydroxybutyl)thia- zolidine-4-carboxylic acid (CGUA), a cysteine derivative conjugated with glucuronic acid, on total glutathione and t otal cysteine contents in rat tissues were investigated. Total glutath ione (GSH and GSSG) and total cysteine (cysteine and cystine) were det ermined by a new method consisting of preparation of S-carboxymethylgl utathione (CMSG) and S-carboxymethylcysteine (CMC), respectively, and subsequent analyses with an amino acid analyzer. CGUA was determined b y a coloration method employing an acidic ninhydrin reagent. Total cys teine contents in liver, kidney and plasma rapidly increased to 2.3, 2 .7 and 6.5 times the levels of the controls, respectively, after CGUA administration at a dose of 5 mmol/kg of body weight. Total glutathion e content did not change significantly in the liver or blood except fo r the kidney with a significant increase during the first 1-h period a fter administration. CGUA content increased markedly in these tissues, especially in the kidney, and 30% of administered CGUA was excreted i n urine within 2h. These results indicate that CGUA is converted into cysteine in vivo, suggesting the usefulness of this compound for prote ction of the kidney and the liver.