Contribution of Chloride Channel Conductance to the Regulation of Resting Membrane Potential in Chondrocytes

Abstract

The contribution of Cl⁻ conductance relative to that of K⁺ in the regulation of membrane potential was examined using OUMS-27 cells, a model cell-line of human chondrocytes. Application of 100 μM niflumic acid (NFA) and other anion-channel blockers induced significant membrane hyperpolarization. The NFA-sensitive membrane current under voltage-clamp was predominantly Cl⁻ current. Application of NFA induced small but significant increase in intracellular Ca²⁺ concentration ([Ca²⁺]_i) and markedly enhanced the late component of [Ca²⁺]_i rise induced by 1 μM histamine. In conclusion, Cl⁻ conductance substantially contributes to the regulation of resting membrane potential and [Ca²⁺]_i in OUMS-27 cells.