Macro and Micro Autoradiographic Studies on Oxalate in Normal and Hyperoxaluric Rats

It is known that the deposition of calcium oxalate crystals in the kidney is the first stage of stone formation. However, the exact location of this deposition in the kidney has not been determined. Hautmann and Oswald1 pointed out that there was a concentration gradient of oxalate and calcium from cortex to medulla of the kidney, and that oxalate and calcium contents in the papilla were hundred times higher than those in urine. These findings indicated that the renal papilla, especially the interstitium of papilla might be the site of the calcium oxalate crystalluric deposition. In the present study, we performed autoradiographic studies on oxalate in hyperoxaluric rats using 14C-oxalate, in order to elucidate the distribution of oxalate in renal tissue and the site of the deposition of calcium oxalate crystals along the nephron.