[Effect of ion channel modulators on the membrane potential of human chondrocytes]

As all living cell systems, human chondrocytes are provided with a membrane potential. For its origin the existence of ion channels at the cell membrane is an essential prerequisite. In non-human chondrocytes, different ion channels could already be identified. A connection between the potassium channel activity and the proliferation has been detected in different human cell systems. Whereas, the proof of a connection between ion channel activity of human chondrocytes and the proliferation has yet to be established. In this study the concentration-dependent influence of the ion channel modulators tetraethylammonium (TEA), 4-amino-pyridin (4-AP), 4',4'diisothiocyanatostilbene-2,2'disulfonic acid (DIDS), 4-acetamido-4'isothiocyano-2,2'disulfonic acid stilbene (SITS) and verapamil on the membrane potential and the proliferation of human chondrocytes was investigated using flow cytometry. The results show an effect of the used ion channel modulators causing a change of the membrane potential of human chondrocytes. The decrease of the membrane potential by 18% was measured with 0.25 mmol/l verapamil meaning the maximal measurable effect compared with a control group. When measuring DNA distribution, it became apparent that the human chondrocytes are diploid cells with a very low proliferation tendency. These results allow the conclusion of an influence of ion channel modulators on chondrocyte proliferation.