We present the first integrated circuit (IC) for scalable, high-throughput in vitro intracellular electrophysiology with simultaneous recording and stimulation implementing all functions of signal amplification, acquisition, and control directly interfacing with electrodes integrated on-chip. The 2.236~mm X 2.236 mm IC in 180nm CMOS contains four 8 X 8 arrays of nanowire electrodes at 50 um pitch deposited over top-metal on the IC surface, for a total of 256 channels. Each channel consumes 0.47 uW of power for current stimulation and voltage recording across 80~dB range at 25 kHz data rate.