Sulfate metabolism in experimental diabetes.

Previous studies have indicated altered rates of sulfate clearance in experimental diabetes, but have disagreed on the magnitude and direction of change of serum sulfate, or its impact on tissue sulfate concentrations. The present study was undertaken in order to investigate the temporal effects of streptozotocin-induced diabetes on sulfate pools in the rat. In contrast to some earlier reports, we found no effects of diabetes on serum sulfate concentrations throughout 12 weeks of disease, as measured by ion chromatography. However, marked increases in sulfate concentration were found in liver cytosol (3.5-fold; p less than 0.0005) and kidney (1.7-fold; p = 0.002) by 7 weeks. The measurement of inulin space demonstrated that the changes in hepatic sulfate were due to increased concentrations of the ion in the cell cytosol. Normal serum sulfate concentrations, together with reports of increased renal clearance of sulfate in diabetes, suggest an intracellular origin of the excess cytosolic sulfate. Glucose did not affect the uptake of sulfate by renal mesangial cells in culture. These aberrations in sulfate metabolism are not such as to compromise biological sulfation reactions, and cannot account for reported changes in the incorporation of sulfate into basement membrane proteoglycans during diabetes.