(A,B) Mean current-voltage relation recorded from the cell body (A, n = 6) or a motile cilium (B, n = 5) after break-in in aCSF (filled squares), subsequent cell uncoupling with flufenamic acid (FFA, 100 μM, 2 min, filled circles), or block of K+ conductances in TEA-Cl/BaCl2 (TEA/Ba2+, filled diamonds; only cell/cilium recordings with input resistance >1 GΩ after TEA-Cl/BaCl2 treatment are plotted). Holding potential between 200 ms steps, -80 mV. Note: The voltage in A and B refers to the command voltage. The voltage error, that is, the difference between the command voltage and membrane voltage produces a large error due to the high resistance through the cilium in series with the low, multicellular membrane resistance (resting K+ conductance, cell-cell connections via gap junctions). Thus, large currents are inaccurate: the top traces only serve to show that flufenamic acid uncouples cells. (C) Example capacitive currents recorded in response to a 20 mV hyperpolarizing voltage step (50 ms) for the cell body (black) and motile cilium (green) after uncoupling with flufenamic acid (FFA, 100 μM) and block of K+ conductances (TEA-Cl/BaCl2). The steady state (time-independent) current in the motile cilium trace is leak current. (D–F) Time constant (D), membrane capacitance (E), and series resistance (F) determined from an average of 100–200 sweeps of capacitive current for cell body (black squares) and motile cilium (green squares) recordings after cell uncoupling with flufenamic acid (FFA, 100 μM, ~5 min) and perfusion with TEA-Cl/BaCl2 (TEA/Ba2+, n = 7–8). (G) Resting membrane potential assessed under current clamp with a gramicidin-perforated patch for cell bodies (black squares) and motile cilia (green squares) before (n = 7 cell body, n = 8 motile cilia) and after (n = 7 cell body, n = 5 motile cilia) addition of flufenamic acid (FFA, 100 μM) to the bath. Open squares represent the range of individual cells/cilia; filled squares are the mean. Error bars; ± SEM. (H) Cartoon illustrating simplified equivalent circuit of access to the cellular compartment via a motile cilium. The cable-like properties of a motile cilium significantly increase the access (series) resistance. Block of gap junctions by flufenamic acid removes the contributions from neighboring cells.