Dose-dependent effect of glucosamine hydrochloride (a) and glucosamine sulfate (b) on release of [3H]-proline-labeled collagen matrix by activated chondrocytes. [3H]-proline-labeled monolayer of primary articular chondrocytes was stimulated with A23187 (10 μM) in the absence or presence of increasing concentrations of glucosamine hydrochloride and glucosamine sulfate. The results are presented as the mean of triplicate set of wells ± standard error. A representative experiment is shown. *Statistically significant between cells stimulated with calcium ionophore and with glucosamine hydrochloride or glucosamine sulfate. Ca Iono, calcium ionophore; Glu, glucosamine hydrochloride; GS, glucosamine sulfate.