UNIQUE DISTRIBUTION PROFILES OF GLUTATHIONE S-TRANSFERASES IN REGIONSOF KIDNEY, URETER, AND BLADDER OF RABBIT

BACKGROUND: Glutathione S-transferases detoxify a broad range of exoge nous compounds, but are important also in the metabolism of endogenous compounds. Physiologically relevant substrates are the endoperoxide a nd hydroperoxide metabolites of arachidonic acid that play important r oles in many tissues including the kidney. EXPERIMENTAL DESIGN: We use d immunohistochemical and immunoblotting techniques in a systematic st udy of renal localization of four rabbit enzymes that represent three major mammalian cytosolic glutathione S-transferase classes, alpha, pi , and mu. RESULTS: The two alpha-class enzymes (rbGST alpha I, rbGST a lpha II) were distributed discretely in kidney, ureter, and bladder, w hile pi and mu were widely distributed in the renal system. Immunohist ochemical localization in paraffin sections with antibodies specific f or rbGST alpha I or rbGST alpha II demonstrated that no compartment of the renal system contained both enzymes. Collecting ducts of the inne r medulla and all epithelial cells of the kidney pelvis, ureter, and b ladder contained rbGST alpha I. All cells lining proximal tubules cont ained rbGST alpha II. No other compartment of the renal system exhibit ed immunoreactivity with anti-rbGST alpha II. Antibody specific for pi reacted with cells lining nephrons, ureter, and bladder and with endo thelial cells throughout the renal system. Localization of pi was most prominent in the collecting ducts of medulla and in the epithelial ce lls lining the kidney pelvis, ureter, and bladder. As anti-mu did not react in tissue sections, distribution of mu was determined by immunob lotting. Immunoblots of cytosolic preparations from whole kidney, cort ex, medulla, and epithelia of ureter, bladder, and kidney pelvis were prepared and tested with each of the 4 antibodies. This second localiz ation method confirmed the distribution data from tissue sections for rbGST alpha I, rb GST alpha II, and pi; also, it demonstrated that the staining observed in tissue was specifically for each enzyme. mu was detected in all the renal cytosolic preparations except those from the epithelium of the kidney pelvis. CONCLUSIONS: The discrete renal dist ribution of rbGST alpha I and rbGST alpha II and their distinct cataly tic activities with prostaglandin substrates suggest important roles f or these enzymes in prostaglandin-dependent renal functions.