Fig. 1.

Sustained cholinergic activation evokes delayed transient postsynaptic currents. A1: a train of 10 shocks at 40 Hz elicits a facilitated and summated postsynaptic response in a young [postnatal day (P) 9] inner hair cell (inward going at a holding potential of −94 mV). Delayed release is seen as randomly timed transient membrane currents that continue long after the last shock. A2: delayed transient currents expanded and enlarged, beginning near the asterisk in A1. B1: application of 1 mM ACh evoked a large inward current at −94 mV followed by numerous small transient currents. B2: transient currents expanded and enlarged beginning near the time marked by asterisk in B1. The membrane current (Im) of the cells is presented as a function of time.