A Novel Cell Volume Sensor for Real-Time Analysis of Ca²⁺-Activated K⁺ Channel

Potassium channels play a vital role in cell volume regulation. A cell volume sensor was constructed by integrating regulatory volume decrease (RVD) with quartz-crystal microbalance (QCM) for studying potassium channels and their expression. The sensor successfully monitored the K⁺ channel's activities during RVD by sensitive and noninvasive means. It showed that Ca²⁺ activated the K⁺ channel (K_Ca) and enhanced the RVD level. The inhibition of blockers on K⁺ channels exhibited an obvious difference in RVD level between normal and cancerous nasopharyngeal cells, suggesting that the K_Ca channel contributes a dominant role to the RVD function and provides an approach to identify the activation of various K⁺ channels.