Sulfite Inhibits Oxalate Production from Glycolate and Glyoxylate in Vitro and from Dichloroacetate Infused IV into Male Rats

The effect of sulfite on oxalate production from glycolate and glyoxylate was investigated in an in vitro assay system using rabbit muscle LDH and rat liver 35-60% ammonium sulfate fraction as enzymes, A ≥ 50% inhibition in oxalate production was observed at sulfite to glyoxylate ratio of 0.4. LDH activity (change in A₃₄₀ nm) was inhibited by ≥40% at sulfite to glyoxylate ratio of 0.5. Male Sprague-Dawley rats fasted for 24 h and infused with dichloroacetate (150 mg/rat/h, iv, n = 6), without and with sodium sulfite (150 mg/rat/h, n = 6) excreted oxalate in urine, respectively, at the rate of 1.13 ± 0.29 and 0.61 ± 0.09 μmol/h/100 g body wt, showing a nearly 50% reduction due to sulfite. The present report demands further experimentation to define the role of sulfite as an intracellular modulator of oxalate production.