[Spin-lattice-relaxationtime-T1 measurements of hyaluronic acid (author's transl)].

Reductions with [3H5NaBH4 proof that the decrease in viscosity of hyaluronic acid solutions caused by lowering the pH does not depend on a depolymerisation of hyaluronic acid. At the same time investigations at different pH-values, show a sigmoide increase of the Spin-Lattice-Relaxationtime T1. This increase depends on a progressive aggregation of the hyaluronic acid molecule. The effect seems to be induced by the decrease of ionization of the carboxylgroups, by acidification of the solution.