Membrane noise and intercellular communication

Voltage noise has been recorded with intracellular glass microelectrodes from spheroidal aggregates of embryonic heart cells in culture. Beating was suppressed with tetrodotoxin. Input resistance and noise decreased as external potassium increased. Cross correlation of noise from two cells in an aggregate was used to measure their electrical coupling. Current injected through a third electrode permitted an independent measure of intercellular communication. Coupling resistance was found to be less than 10 percent of the aggregate input impedance, and to be frequency-independent from dc to 160 Hz.