Figure 4Acquisition of the low-voltage-activated conductance, *G*_{K,L}, at approximately E18

*A*, A representative family of currents recorded from a putative type I hair cell. The voltage protocol (below) was identical to that used to evoke the currents in . The dashed line shows the zero-current level. *B*, A hyperpolarizing prepulse to−124 mV deactivated the currents that were active at rest. A subsequent family of depolarizations (bottom traces) was used to reactivate the currents. Same cell as in *A*. Fits of are superimposed on the three middle traces (gray lines). The dashed line indicates the zero-current level. *C*, Activation curves derived from the data shown in *B* (open circles) and, for comparison, from the delayed rectifier conductance of a typical E18 hair cell (filled circles). Both datasets were fit with Boltzmann equations with a *V*_{1/2} of −66 and −28 mV, an *s* of 6.8 and 5.6 mV, and a *G*_{Max} of 34 and 16 nS, respectively. *D*, Bar graph of mean maximum chord conductance for *G*_{K,L} at each developmental stage. Only cells with *G*_{K,L} were included in the mean. Error bars show SD. The fraction indicates the number of cells with *G*_{K,L} over the number of cells studied at each stage. Note that the study was not done blind and that we sometimes targeted cells with type I morphological features. Therefore, the ratios do not represent the proportion of type I cells in the developing utricular epithelium.

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