Modelling the Ion Channel Behaviour of Articular Chondrocytes

All cells have a membrane potential; this voltage difference arises from the different intracellular and extracellular ion concentrations. In excitable tissue the cell membranes contain ion channels which control the movement of ions and hence control the cell’s membrane potential. Extensive measurements of the electrophysiology of excitable cells has allowed considerable understanding of the ion channels. The Hodgkin-Huxley model [1] was developed from measurements on a squid nerve axon, and it quantifies the changes in membrane conductance due to the opening and closing of specific ion channels. This model has been very successful in describing the electrical behaviour of neurons. Ion channels also exist in non-excitable tissue cells. Patch clamp experiments have demonstrated that ion channels in chondrocytes influence cell’s membrane potential [2]; controls the influx of Ca²⁺ [3] and may regulate cell proliferation [2]. The objective of this research was to develop a model of ion channel behaviour for connective tissue cells based on the Hodgkin-Huxley model, and to apply this model to reported patch clamp measurements of articular chondrocytes.