Contribution of chloride channel conductance to the regulation of resting membrane potential in chondrocytes.

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 microM 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 Ca(2+) concentration (Ca(2+)) and markedly enhanced the late component of Ca(2+) rise induced by 1 microM histamine. In conclusion, Cl(-) conductance substantially contributes to the regulation of resting membrane potential and Ca(2+) in OUMS-27 cells.