The cellular physiology of articular cartilage

The cells of articular cartilage, or chondrocytes, live in an unusual and constantly changing physicochemical environment. They receive poorly understood signals during the loading of the tissue and produce, through a balance between macromolecular synthesis and degradation, a mechanically resilient extracellular matrix. Matrix turnover is influenced by changes to the intracellular composition (cell volume, pH and ionic content) of chondrocytes, and there are suggestions that this is altered in the disease process of osteoarthrosis. However, there is little information on the fundamental aspects of articular cartilage cellular physiology, which is essential if the factors controlling cartilage integrity in health and disease are to be understood. The present short review focuses on some of the membrane transporters of chondrocytes involved in volume regulation, electrophysiology and the regulation of intracellular pH.