Fig. 6.
Biophysical properties of currents evoked by bath application of nicotine in a T stellate cell (A–C). A, Nicotine (5 μm) increased the instantaneous current (IINS), elicited a negative shift of the holding current, and increased membrane noise. B, The nicotine-evoked difference currents (currents in nicotine minus control currents) obtained from trace-to-trace subtraction. C,I–V relationship of the difference current. The extrapolated reversal potential was −9.5 mV, calculated by the linear fit to the plot. The current amplitudes were averaged through the whole length of each trace. D, No response was evoked in a D stellate cell. The internal solution was normal. The external solution contained 0.5 μm TTX, 40 μm DNQX, and 1 μm strychnine. Note differences in the magnitude and rate of rise of the hyperpolarization-activated currents for the most hyperpolarized pulses (τ = 98 msec in A and 34 msec in D).