Fig. 3. Dual whole-cell voltage-clamp recordings from dye-coupled IHCs reveal bidirectional low resistance electrical coupling.
a, b After observing IHC-to-IHC diffusion of LY from the loaded IHC (C1), the second neighboring coupled IHC (C2) was patched with a LY-free pipette (left). c, d Exemplary dual recording of coupled IHCs (3 recordings in total) demonstrates how depolarizations of one of the IHCs from holding potential (VH, −70 mV) produces junctional currents (IJ) in the second IHC held at VH. e, f In the absence of dye coupling, no IJ was observed (cyan in g). g The steep linear IJ–VJ curve indicates a large, ohmic conductance between the dye-coupled IHCs (purple, n = 3). Negligible conductance is observed in non-coupled IHCs (cyan, n = 3). h An electrical circuit equivalent of coupled IHCs (cell capacitance, C1 = C2 = 10 pF; junctional resistance, RJ = 10 MΩ (filled box in i) or 100 MΩ (empty box in i); Cell membrane resistance, RM1 = RM2 = 1 GΩ; Series resistance, RS1 = RS2 = 10 MΩ) (i) produces IJ values that frame those of coupled IHCs (n = 3, compare with g). VJ, junctional voltage difference, IJ junctional current, LY lucifer yellow.