Synovial fluids facilitate small solute diffusivity.

The diffusivity of water, fucose, proline, lysine, glutamic acid, glucose and sucrose was determined in a variety of inflammatory human synovial fluids. In view of the constituents of pathological synovial fluids one would predict impedence to solute movement. In several fluid diffusivity was enhanced relative to translational diffusion in water. In most fluids diffusivity was enhanced relative to diffusion in diluted serum. Diffusivity of the solutes was dependent on size and charge of the solute but independent of fluid characteristics, including glucose, protein, and complement concentrations and cellular constituents. This paper reports aberrant small solute behaviour in synovial fluids. Enhanced diffusivity relative to water was demonstrated in hyaluronate dissolved in diluted serum as well. Hyaluronate domains in the synovial fluids interact with these solutes, facilitating movement. This phenomenon affords a homoestatic mechanism as regards chondrocyte viability in spite of inflammation or a low glucose concentration.