I_tail recorded in the rod bipolar cell is activated by Ca²⁺ influx.

<p>(<b>A, B</b>) The cells that retained their axon terminals were filled with Lucifer Yellow during recording and were morphologically identified under a fluorescence microscope after recording (left panel). The inwardly generating I_Ca was recorded from a voltage-clamped bipolar cell with a retained axon terminal at the voltage of +10 mV from a holding potential of −85 mV; subsequently, I_tail was activated when returned to the holding potential. <b>C</b>. A solution containing zero Ca²⁺, a control solution (5 mM Ca²⁺), and a solution of 3 mM Co²⁺ were applied serially (n = 13). Currents were recorded from a voltage-clamped bipolar cell with a retained axon terminal at the voltage of +10 mV from a holding potential of −85 mV. <b>D</b>. Ca²⁺ was replaced with Ba²⁺ in the extracellular solution (n = 10). <b>E</b>. BAPTA/AM (0.1 mM), which is a membrane-permeable Ca²⁺ chelator, was applied extracellularly to show the time course of changes in I_tail. Scale bars, 5 µm.