Sub-Millivolt Voltage Imaging Reveals Gap Junction-Mediated Bioelectric Contact Inhibition

Sub-millivolt membrane potential (Vm) dynamics in multicellular non-excitable networks have remained largely invisible due to a lack of sufficiently sensitive imaging tools. Here, we introduce rEstus2s, a next-generation genetically encoded voltage indicator that overcomes this barrier by enabling high-resolution Vm imaging across the full physiological resting Vm range (-100 to 0 mV). Using rEstus2s, we uncover bioelectric contact inhibition (BCI), a fundamental biophysical principle where gap junction coupling acts as a passive noise filter to stabilize Vm. We demonstrate that the time-dependent variance of Vm (electrical volatility) relative to the number of cells (n) in a network follows a 1/n scaling law, reflecting a transition from stochastic single-cell behavior to collective electrical stability. While Ca2+-activated oncogenic ion channels, including ANO1 and KCa3.1, promote pronounced electrical volatility in isolated cells, BCI effectively attenuates volatility in electrically coupled networks. Disruption of gap junction coupling in cancer cells abolishes BCI and restores high electrical volatility. These findings establish a unifying biophysical framework for understanding how multicellularity maintains electrical homeostasis in health and disease. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=168 SRC="FIGDIR/small/701308v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@120fcb9org.highwire.dtl.DTLVardef@affa2aorg.highwire.dtl.DTLVardef@150ffa7org.highwire.dtl.DTLVardef@c05392_HPS_FORMAT_FIGEXP M_FIG C_FIG