Fig. 2.
Recorded cells from primary cultures of dissociated cortex have electrical properties of neuroblasts. Small cell clusters (∼10–50 cells) from E12 telencephala were examined between 2 and 20 hr after plating and examined as small aggregates.a, Fast transient inward currents (negative values in the figure) could be observed in LPA-responsive cells. Whole-cell currents were elicited by voltage steps (40 msec duration) between −58 and +42 mV in increments of 20 mV from a holding potential of −98 mV. The peak inward current was −15.6 pA/pF. b, The current–voltage relationship of the voltage-activated currents elicited for the neuroblast shown in Figure 2a. Peak inward (Iin; circles) and steady-state outward (Iout;squares) currents (in picoamperes) are plotted against the step voltage. c, The fast transient inward currents are TTX-sensitive. Whole-cell currents were elicited by voltage steps to −68, −28, 2, and 32 mV from a holding potential of −98 mV. The recording electrode contained Cs+ IS; bath contained Tyrode’s. Left, Fast transientIin (−12.3 pF/pA) before bath puffer application of TTX (2 μm); center, during exposure to TTX; right, partial recovery 3 min after washout of TTX.