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Abstract
Recently, we have developed a microelectrode array to measure streaming potentials across the cartilage articular surface in unconfined compression geometry. We have constructed a linear array of 8 platinum (80%) and iridium (20%) wire electrodes of 50 $\mu$m diameter separated by 300 $\mu$m.
Cartilage disks were isolated from the humeral head of a 1 to 2 year old steer. The 4 mm disks were cultured in an incubator at 37$\sp\circ$C and 5% CO$\sb2$. The serum-free media (DME/F12) was supplemented with 50 $\mu$g/ml of gentamycin, 0.01% of bovine serum albumin (BSA) and 20 $\mu$g/ml of ascorbate. Cartilage disks were matched in triplets: a control disk, a cartilage explant treated with a degradation agent and a disk frozen immediately after isolation. Two degradation agents were used. The interleukin-1$\alpha$ (IL-1$\alpha$) is a cytokine which inhibits proteoglycan and collagen synthesis and increases metalloproteinase (MMP) production. The MMPs are responsible for extracellular matrix degradation. The aminophenylmercuric acetate (APMA) also activates the latent forms of the MMPs. We did three different experiments. During the first one, disks were placed in culture for 13 days with and without 5 ng/ml of IL-1$\alpha$. The second experiment was performed to study the evolution of IL-1$\alpha$ degradation with time of culture. During a third experiment, cartilage explants were treated with 1 mM of APMA. (Abstract shortened by UMI.)
