Toshinao Kanazawa

fate of circulating oxalate in rats

The pharmacokinetics of oxalate were studied in normal and nephrectomized rats with the use of radioisotope-labelled oxalate. The disappearance of [14C]oxalate from the plasma was analyzed with a two-compartment open model. The pharmacokinetic parameters of oxalate were compared with those for inulin. In normal rats, the plasma half-life of the elimination of oxalate was 0.33 +/- 0.06 h and that for inulin was 0.26 +/- 0.05 h (n = 10, mean +/- SD). The volume of distribution for oxalate was 56.7 +/- 6.80 and that for inulin 34.0 +/- 4.79 ml/100 g body weight, indicating that oxalate has access to additional compartments besides the extracellular volume. The total clearance of oxalate was 1.2 times higher than that for inulin. In nephrectomized rats, however, the plasma half-life of the elimination of oxalate was 1.85 +/- 0.34 h (n = 7, mean +/- SD) and that for inulin was 4.26 +/- 0.78 h. The total clearance of oxalate was 177 +/- 29 and that for inulin was 30 +/- 5 microliters/min/100 g body weight. In order to identify the extrarenal elimination route of oxalate, the bile of nephrectomized rats was collected. The hepatic clearance of oxalate was 31.2 +/- 2.7 microliters/min/100 g body weight. The biliary excretion of oxalate accounts for 17.6% of the total clearance in nephrectomized rats. Thus, other elimination processes of oxalate besides renal and hepatic clearance take place.

Concentration gradient of oxalate from cortex to papilla in rat kidney

Abstract Background: The kidney eliminates the major fraction of plasma oxalate. It is well known that oxalate is freely filtered by glomeruli and secreted by the proximal tubules. However, the renal handling of oxalate in distal nephrons, which is considered as playing an important role in stone formation, remains obscure.

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.

Autoradiographic Study of Oxalate in Rats

We have already reported pharmacokinetic studies of oxalate in rats using radio-isotopes; oxalate is more diffusible through biological membranes than inulin, and oxalate is excreted mainly by the kidney, although some is excreted by the liver (Sugimoto et al. 1988). Here, we checked these results in an autoradiographic study of oxalate in rats. Autoradiograms made after an injection of [14C]oxalate were com-pared with those made after an injection of [14C]inulin.

Immune Response of Urolithiasis Patients Treated by Extracorporeal Shock Wave Lithotripsy or Transurethral Ureterolithotripsy

Peripheral blood mononuclear cells (PBMN) from healthy donors and urolithiasis patients before and after extracorporeal shock wave lithotripsy (ESWL*) or transurethral ureterolithotripsy (TUL) were harvested using Ficoll-Paque gradient in order to study the effects of shock waves on PBMN.