Oxygen Consumption Rates of Temporomandibular Joint Disc Cells

Methods: Cells were isolated from 8-10 months old porcine TMJ discs. The changes in oxygen tension were recorded when cells were cultured in a sealed metabolism chamber. The rate of oxygen consumption of TMJ disc cells was determined by theoretical curve-fitting using the Michaelis-Menten equation. The oxygen consumption rates were measured over a range of glucose concentrations (0.5, 1, 5, and 25mM) and pH levels (6.2, 6.8, and 7.4).

Results: The oxygen consumption rate of disc cells decreased as oxygen tension decreased. The rate fell by 50% as oxygen concentration decreased from 21% to 4%. Cells cultured in different glucose concentrations exhibited no significant differences in oxygen consumption rates, while it was significantly affected by pH. The oxygen consumption rate of cells cultured at pH 6.2 was significantly greater than that at pH 6.8 and 7.4.

Conclusion: The average oxygen consumption rate of TMJ disc cells measured in this study was about 10 times higher than that of cartilage chondrocytes and intervertebral disc cells. The oxygen consumption rate of TMJ disc cells, unlike chondrocytes, was not regulated by glucose concentration via the Crabtree effect. The possible reason is that TMJ disc has multiple cell types with about 70% fibroblastic cells. This study will provide a better understanding of the transport of oxygen in the TMJ discs. (Supported by NIH P20RR-016461 and P20RR-017696).