A Ca2+ - and pH-Dependent K+ Channel of rat C6 glioma cells and its possible role in acidosis-induced cell swelling

✍ Scribed by Dr. Michael Strupp; Frank Staub; Peter Grafe

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 932 KB
• Volume: 9
• Category: Article
• ISSN: 0894-1491
• DOI: 10.1002/glia.440090207

✦ Synopsis

The aim of the present study was to explore whether a change in membrane K+ conductance contributes to acidosis-induced swelling of cultured rat C6 glioma cells. Electrophysiological studies were performed using whole-cell and single-channel recordings in combination with cell volume measurements in cell suspension by flow cytometry. Whole-cell recordings revealed a voltage-dependent K+ conductance. The predominant K' channel in single-channel recordings with symmetrical high K ' concentrations was inwardly rectifying and had conductances of 35 and 15 pS, respectively. A raised internal free Ca" concentration and membrane depolarization increased the open probability of this channel. Internal acidosis (pH 6.4-5.41, on the other hand, reduced open probability and single-channel conductance. Both whole-cell and single-channel K' currents were blocked by quinidine (0.1-1 mM), which was therefore used to analyze the functional consequences of a n inhibition of this conductance for cell volume. Thereby, quinidine (1 mM) produced a small (5%) and transient cell swelling of C6 glioma cells. In contrast, acidosis (pH 5.6) caused a much larger (about 20%) and maintained swelling. Since quinidine produced only a minor swelling of C6 cells, it is unlikely that inhibition of the K+ conductance caused acidosis-induced cell swelling. Other mechanisms, such as activation of ion transporters, must therefore be responsible.