The degradation of glutathione derivatives in the rat kidney.

: Single proximal rat kidney tubules and Henle loops were microperfused with labelled S-substituted glutathione derivatives which are physiological mercapturic acid precursors. S-methyl-glutathione as well as the non-permeating bromo-sulfaleinglutathione adduct were degraded in the proximal convolution with a half-life of about 3.5 sec. The findings demonstrate that the brush-border membrane-bound renal gamma-glutamyl transpeptidase acts on luminal substrates and is involved in mercapturic acid synthesis and splitting of extracellular glutathione.