Influence of a three-day incubation with TNFα (100 ng/ml), the NO synthetase inhibitor L-NMMA (1 mM), and the TIMPs (0.1 μM) on the GAG-release, NO production and gene expression level of bovine meniscal tissue explants. (a) Cumulative glycosaminoglycan (GAG) release (n = 6). (b) Cumulative nitric oxide (NO) production, measured by photometrical detection of nitrite accumulation (n = 6). (c) Influence of tissue inhibitors of metalloproteinases (TIMPs) on TNFα-dependent GAG release (n = 5). (d) TNFα-dependent mRNA levels given as a ratio: the x-fold expression level compared with un-stimulated control tissue (using the ΔΔCT method with GAPDH as reference gene; control = 1). Each dot represents data from an independent experiment, bars indicate the mean from four independent experiments. (a to c) All values are mean ± standard error of the mean. * significantly different from control, P < 0.05. ADAMTS = a disintegrin and metalloproteinase with thrombospondin motifs; Agg = aggrecan; Coll I or II = collagen type I or II; MMP = matrix metalloproteinase.