Fig. 2.

The serotonin inward current is voltage-independent and accompanied by a conductance increase, with a reversal potential at approximately −25 mV. A, Steady-state current/voltage plots obtained with a ramp depolarization (20 mV/sec) under voltage clamp from −100 to 0 mV before (control) and during application of serotonin (10 μm). Serotonin caused an inward current at potentials negative to −28 mV, reversing to an outward current between −28 and 0 mV. B, The serotonin current derived fromA by digital subtraction is plotted against membrane potential. The current reverses polarity at −28 mV, and the conductance is essentially linear over the voltage range examined.