Figure 2.

Quantitative analysis of (a) MMP-2 and (b)MMP-9 synthesis by bovine articular cartilage. Medium was collected 24 hours after treatment of explants with 100 ng/ml TNF-α or 50 μM C₂-ceramide in the presence or absence of 2-AP (10 mM) and analysed by gelatin substrate zymography. The area (absorbance units) of substrate gel cleared by proMMP-9 and active MMP-9 was measured by scanning densitometry. Each area obtained was related to the gel clearance obtained with the fibroblast-conditioned-medium standard in order to facilitate comparisons between gels. Data shown are arbitrary units per milligram of wet weight of tissue and are expressed as means ± SEM. *Significantly different from control explants at P < 0.05; **P < 0.01. 2-AP, 2-aminopurine; MMP, matrix metalloproteinase; TNF, tumour necrosis factor.