Glutathione-S-Transferase Activity in the Rabbit Nephron: Segmental Localization in Isolated Tubules and Formation of Thiol Adducts of Ethacrynic Acid

Ligandin is a major renal organic anion-binding protein and is the major glutathione (GSH)-S-transferase in the rat, monkey, and man. GSH transferase activity was measured in isolated segments of the normal rabbit nephron using 1-chloro-2,4-dinitrobenzene as substrate. Enzyme activity was confined to the proximal convoluted and proximal straight tubules and was not detectable in the loops of Henle and collecting tubules.Incubation of proximal tubules with [14C]ethacrynic acid resulted in formation of glutathione and cysteine adducts. Loops of Henle and collecting tubules formed significantly less glutathione adduct and no other adducts. GSH transferase in the proximal tubule may thus be important in vivoin the formation of thiolated adducts by the kidney.