Influence of Changes in Calcium Metabolism on Renal Handling of Oxalate in Rats
Clearance and micropuncture studies on the renal handling of oxalate in rats have led to conflicting results. There is wide agreement that oxalate is excreted into the urine 1.1 to 1.4 fold in excess of the filtered load1–4. In micropuncture studies in Sprague-Dawley rats, Weinman et al1 found not addition of oxalate to the filtered amount in the proximal tubule. However, Hautmann and Osswald 2 did not find oxalate secretion in the superficial proximal tubule of rats. In another study by Greger et al3, proximal tubular secretion of oxalate was found in Wistar rats. Since different experimental protocols (infused amount of saline and 14C oxalate) and different rat strains were used in the above cited studies, it was the aim of the present investigation to identify factors that can influence the renal handling of oxalate. In addition, the importance of calcium in controlling oxalate fluxes across the tubular epithelium was studied, to test the hypothesis that calcium in the tubular fluid might trap the oxalate ion.
KeywordsProximal Tubule Sodium Citrate Oxalate Excretion Renal Handling Micropuncture Study
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