Extracellular currents alter gap junction intercellular communication in synovial fibroblasts.

Area of Science:

• Cell Biology
• Biophysics
• Electrophysiology

Background:

• Gap junction intercellular communication (GJIC) is vital for cell-to-cell signaling.
• Connexin43 protein is a key mediator of GJIC.
• The impact of extremely low frequency (ELF) electric fields on GJIC is not fully understood.

Purpose of the Study:

• To investigate the effect of 60 Hz ELF electric fields on GJIC mediated by connexin43.
• To determine if ELF fields alter calcium (Ca2+) influx and membrane potential in synovial fibroblasts and neuroblastoma cells.

Main Methods:

• Exposure of HIG-82 synovial fibroblasts and 5Y neuroblastoma cells to 60 Hz ELF electric fields (0-75 mA/m²).
• Measurement of single channel conductance, current-voltage (I-V) curves, and Ca2+ influx using patch-clamp techniques.
• Analysis of connexin43 protein function in response to ELF field exposure.

Main Results:

• ELF electric fields significantly reduced gap junction channel conductance in HIG-82 cells at 20 mA/m².
• Low current densities (10 mA/m²) of ELF fields significantly increased Ca2+ influx in HIG-82 cells.
• No significant effects on GJIC or Ca2+ influx were observed in 5Y neuroblastoma cells.
• Plasma membrane I-V curves were unaffected, indicating the ELF field's effect on GJIC was not mediated by changes in membrane potential.

Conclusions:

• ELF electric fields can alter GJIC in synovial cells through a mechanism independent of membrane potential changes.
• Calcium influx may play a role in the observed effects of ELF fields on GJIC in synovial cells.
• ELF electric fields have the potential to antagonize GJIC-mediated responses in synovial cells, such as secretory responses to cytokines.