Rabbit bladder-surface mucin: a thermodynamic mechanism for inhibiting bacterial adhesion.

A possible thermodynamic mechanism for the inhibition of bacterial adhesion to the epithelial bladder surface was investigated in rabbits. Contact angles of aqueous polymeric droplets were measured to assess the relative hydration and surface-free energy, of normal and mucin-free bladder surfaces. We measured an angle of 91.2 +/- 1.2 degrees (SEM), n = 37 for the intact mucin surface and an angle of 120.5 +/- 1.2 degrees, n equal 46 for the epithelium after the mucin was removed with acid. These results indicate that mucin makes the epithelial surface significantly more hydrophilic and so produces a very low free energy interface with the urine environment. Such a low energy surface would inhibit bacterial adhesion because the surface already exists at its free energy minimum.