Unique distribution profiles of glutathione S-transferases in regions of kidney, ureter, and bladder of rabbit.

BACKGROUND

Glutathione S-transferases detoxify a broad range of exogenous compounds, but are important also in the metabolism of endogenous compounds. Physiologically relevant substrates are the endoperoxide and hydroperoxide metabolites of arachidonic acid that play important roles in many tissues including the kidney.

EXPERIMENTAL DESIGN

We used immunohistochemical and immunoblotting techniques in a systematic study 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 alpha II) were distributed discretely in kidney, ureter, and bladder, while pi and mu were widely distributed in the renal system. Immunohistochemical localization in paraffin sections with antibodies specific for rbGST alpha I or rbGST alpha II demonstrated that no compartment of the renal system contained both enzymes. Collecting ducts of the inner medulla and all epithelial cells of the kidney pelvis, ureter, and bladder contained rbGST alpha I. All cells lining proximal tubules contained rbGST alpha II. No other compartment of the renal system exhibited immunoreactivity with anti-rbGST alpha II. Antibody specific for pi reacted with cells lining nephrons, ureter, and bladder and with endothelial cells throughout the renal system. Localization of pi was most prominent in the collecting ducts of medulla and in the epithelial cells lining the kidney pelvis, ureter, and bladder. As anti-mu did not react in tissue sections, distribution of mu was determined by immunoblotting. Immunoblots of cytosolic preparations from whole kidney, cortex, medulla, and epithelia of ureter, bladder, and kidney pelvis were prepared and tested with each of the 4 antibodies. This second localization 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 distribution of rbGST alpha I and rbGST alpha II and their distinct catalytic activities with prostaglandin substrates suggest important roles for these enzymes in prostaglandin-dependent renal functions.