HPLC analysis of GAGs in urinary stones

Glycosaminoglycans (GAGs) have been identified as one of the macromolecules present in the stone matrix. Although electrophoresis has been used to analyze the composition of GAGs, this method is laborious and insensitive. The aim of this study was to examine GAG profiles in the stone matrix from 4 types of stones using high-performance liquid chromatography (HPLC). This method has been shown to be rapid, accurate, and highly sensitive. We could isolate and quantitate the amounts of matrix GAGs in various stones. In the calcium and uric acid stones, the predominant GAG component was heparan sulfate (HS) followed by chondroitin 4 sulfate (Ch-4S) or chondroitin 6 sulfate (Ch-6S), respectively. Chondroitin (Chon) and hyaluronic acid (HA) were absent or present in small amounts. In the MAP stones, the predominant GAG component was ChS and Chon, followed by HA. HS was not detected in magnesium ammonium phosphate (MAP) stones. In conclusion, the process of selective inclusion of GAGs into calcium and uric acid stone matrix is more greatly related to binding affinity than to urinary GAG concentration. The GAGs present in MAP stone matrix differed from those in other types of stones which suggests that the inclusion of GAGs into MAP stone matrix is dependent up on the concentration of urinary GAGs.