期刊
JOURNAL OF MEMBRANE BIOLOGY
卷 185, 期 1, 页码 75-81出版社
SPRINGER-VERLAG
DOI: 10.1007/s00232-001-0112-3
关键词
chloride channel; membrane potential; articular chondrocytes; SITS; patch clamp; rabbit
Membrane conductance of cultured rabbit articular chondrocytes was characterized by means of the patch-clamp technique. The resting membrane potential of the articular chondrocytes was about -42 mV. The membrane potential shifted in accordance with the prediction by the Nernst equation for Cl(-)when intracellular and extracellular concentrations of Cl- were changed. On the other hand, change in extracellular concentration of K+ produced no shift in the membrane potential of chondrocytes. The Cl(-)channel blocker 4-acetamido-4-isothiocyanatostilbene-2'2-disulfonic acid (SITS) depolarized the membrane potential. These findings suggest that the membrane potential of the chondrocytes is determined mainly by Cl- conductance. Using the cell-attached patch-clamp method, a large unitary conductance of 217 pS was observed in the articular chondrocytes. The unitary current was reversibly blocked by SITS. Therefore, the unitary current was carried by Cl-. The Cl- channel showed voltage-dependent activation and the channels exhibited longlasting openings. Therefore, the membrane potential of rabbit cultured articular chondrocytes was mainly determined by the activities of the large-conductance and voltage-dependent Cl- channels.
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