Summary:The determination of S-(l,2-dicarboxyethyl)glutathione and reduced glutathione (GSH) in the rabbit lens and liver was developed using an isotachophoretic analyser.The recovery of S-(l,2-dicarboxyethyl)GSH from the rabbit liver after ion-exchange treatment was 96.8 ± 11.3% (n = 3). The contents of S-(l,2-dicarboxyethyl)GSH in the rabbit lens and liver were 219.9 ± 29.1 (n = 5) and 44.0 ± 13.5 (n = 8) nmol/g, respectively.The contents of S-(l,2-dicarboxyethyl)GSH in the lens and GSH in the lens and liver of naphthalene-treated rabbits was also determined by this method 24 hours after naphthalene administration, at which time the axial opacity "spichen" was observed at the equatorial region of the lens. The content of S-(l,2-dicarboxyethyl)GSH in the lens decreased in proportion to the content of GSH.During the further development of true lens opacity after naphthalene administration, the S-(l,2-dicarboxyethyl)GSH content further compared with that in the spichen stage, but the S-(l,2-dicarboxyethyl)GSH content of the lens that did not develop true opacity after naphthalene administration returned to the normal level. The change of S-(l,2-dicarboxyethyl)GSH content of the lens in the spichen and true opacity stages coincided with that of GSH content.On the other hand, the content of GSH of the liver decreased markedly until 24 hours after naphthalene administration, then returned to normal, irrespective of whether true opacity did or did not subsequently develop.