Fig. 2.

The current responsible for the plateau potential in CBI-5/6 was carried mainly by Na⁺.A, In normal ASW a plateau potential was generated by a brief depolarizing current pulse and terminated by hyperpolarization. The ability to generate plateau potentials was abolished in a solution with 0 mm Na⁺, despite using several different amplitudes of current pulse from three different starting membrane potentials. The plateau potential returned in wash.B, The plateau potential was unaffected in a solution containing 0 mm Ca²⁺ and 1 mm EGTA but was reduced in amplitude and duration by 0 mm Ca²⁺ and 10 mmCo²⁺ and returned to normal during wash.C, TTX (100 μm) abolished spiking in CBI-5/6 but had no effect on the plateau potential. Some action potentials return during wash. The scale is the same in all sections.