Fig. 9.

The sADP and PP were independent of a Na⁺/Ca²⁺ exchanger.A, Intracellular current injection revealed an sADP and a PP in the presence of 20 μm carbachol. The resting membrane potentials before and after cholinergic stimulation were −70 and −62 mV, respectively. Both the sADP and PP were still observed after substitution of 50 mmLi⁺ for equimolar Na⁺ in the external media. After Li⁺ substitution, the membrane depolarized an additional 9 mV; however, negative DC current was injected to maintain the membrane potential at the presubstitution value. B, In a different neuron, intracellular current injection also revealed an sADP and a PP in the presence of 20 μm carbachol. The resting membrane potentials before and after cholinergic stimulation were −66 and −61 mV, respectively. Both the sADP and PP were still observed after a reduction in bath temperature from 35 to 25°C. The neuron depolarized after temperature reduction, however, negative DC current was injected to maintain the membrane potential at the same value as at 35°C.