Abstract
Taurine, a sulfur amino acid, is present in abundant amounts in cells throughout the body. The kidney regulates taurine balance by modulating proximal tubule reabsorption in response to fluctuations in dietary intake of this nutrient. There is no information about the localization of taurine within the kidney in normal and diseased renal parenchyma. Therefore, using an antibody to a taurine-glutaraldehyde-BSA conjugate, we examined the distribution of taurine in renal tissue. Normal rats, those with streptozocin diabetes, puromycin aminonucleoside nephropathy, bilateral ureteral ligation, and 5/6 nephrectomy were studied. In normal animals, taurine was found primarily in medullary tubules, with minimal staining of proximal tubules and glomeruli. There was increased taurine staining of all structures, especially medullary tubules, in rats with streptozocin diabetes and puromycin aminonucleoside nephropathy. These changes were more pronounced in diabetic rats and were unrelated to renal medullary osmolality. The distribution of taurine within the kidney was unchanged in the models of acute and chronic renal failure. Alterations in the immunohistochemical localization of taurine correlated with the beneficial effect of this amino acid to preserve renal function in the rats with chronic diabetes and puromycin aminonucleoside nephropathy. These results suggest that taurine is preferentially localized in the medullary regions of the kidney, where it exerts a protective effect against renal injury in select disease states.