Concentration and Degree of Polymerization of Hyaluronate in Equine Synovial Fluid

In addition to its well-known physicochemical properties, hyaluronate (HA) has recently been shown to have important biological and pathophysiologic regulatory effects on granulocytes, monocytes, fibroblasts, and endothelial cells, as well as on the healing of wounds and various joint disorders. Many of these effects depend on or are reflected in the concentration and degree of polymerization of HA. Therefore, high-performance liquid chromatography with size-exclusion column was used to characterize the concentration and degree of polymerization of HA in equine synovial fluid (SF). The mean (+/- SD) HA concentration was 0.47 +/- 0.19 mg/ml and there was no difference between control joints and those with positive response to local anesthetic administration (0.61 +/- 0.20 mg/ml vs 0.42 +/- 0.17 mg/ml), suggesting that in horses with acute traumatic synovitis causing lameness, HA concentration in SF cannot be used as a marker for the condition. High-performance liquid chromatograms disclosed considerable variation between horses in the degree of polymerization reflected in the peak area to height ratio (mean +/- SD, 3.207 +/- 0.447; range, 2.229 to 3.915), indicating differences in local synthesis, degradation, or mobilization into lymph of SF HA. In addition, the correlation between SF HA concentration and degree of polymerization was 0.760 (P less than 0.01; linear regression analysis), suggesting that HA concentration and chain length are independently regulated.