Time-dependent inhibitory effect of glucosamine hydrochloride on the release of [3H]-proline-labeled articular collagen matrix. [3H]-proline-labeled monolayer of primary articular chondrocytes was stimulated with A23187 (10 μM) in the absence and presence of glucosamine hydrochloride (50 mM). Glucosamine was added at the initiation (0 hours) or at different times as shown in the figure. The 4-hour percentage release of labeled matrix (collagen) is shown. 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 in the presence of glucosamine hydrochloride. Ca Iono, calcium ionophore; Glu, glucosamine hydrochloride.