Pharmacological sensitivity of I_cs.

<p><i>A</i>: Changes (as compared to break-in) in current amplitude at +40 mV in response to the potential I_cs antagonists: carbenoxelone (100 μM), SKF96365 (100 μM), 2-APB (100 μM), La³⁺ (1 mM) and TEA (40 mM). La³⁺ concentration was reduced to 100 μM when co-applied with TEA. <i>B</i>: Comparison of current amplitudes at +40 mV when recording electrodes contained either Cs⁺ (135 mM) or Cs⁺ + TEA (30 mM of TEA replaced) to block K⁺ channels. <i>P</i> values represent comparison to control, <i>P</i> > 0.05; *<i>P</i> < 0.05, **<i>P</i> < 0.01, ***<i>P</i> < 0.001). Data shown are averages and error bars represent s.e.m.</p

Voltage-dependent activation and deactivation of I_cs.

<p><i>A</i>: Response of a representative neuron to depolarizing voltage steps from a holding potential of -70 mV. Application of voltage steps (lower panel) resulted in outward currents (upper panel, solid lines) which were fitted mono-exponentially (dashed lines). <i>B</i>: Hyperpolarizing steps (lower panel) from +20 mV, resulted in inward tail currents (upper panel, solid lines). Deactivation of I_cs was voltage-dependent and was also fitted with single exponentials (dashed lines). <i>C</i>: Time constants of activation (empty squares) and deactivation (filled squares) as a function of membrane voltage (n = 5 neurons).</p

Pharmacological sensitivity of I_cs.

<p><i>A</i>: Changes (as compared to break-in) in current amplitude at +40 mV in response to the potential I_cs antagonists: carbenoxelone (100 μM), SKF96365 (100 μM), 2-APB (100 μM), La³⁺ (1 mM) and TEA (40 mM). La³⁺ concentration was reduced to 100 μM when co-applied with TEA. <i>B</i>: Comparison of current amplitudes at +40 mV when recording electrodes contained either Cs⁺ (135 mM) or Cs⁺ + TEA (30 mM of TEA replaced) to block K⁺ channels. <i>P</i> values represent comparison to control, <i>P</i> > 0.05; *<i>P</i> < 0.05, **<i>P</i> < 0.01, ***<i>P</i> < 0.001). Data shown are averages and error bars represent s.e.m.</p

I_cs in cortical layer 5 pyramidal neurons.

<p><i>A</i>: Whole cell, voltage clamp recording while blocking Na⁺ currents with TTX (1μM), Ca²⁺ currents with Cd²⁺ (200μM) and Cs⁺ (135mM) in the recording pipette to block K⁺ currents. Voltage steps (10 mV increments) revealed an outward current at voltages more depolarized than -20mV. <i>B</i>: In the same cell, a slow (110 mV/s) voltage ramp (-70 to +40 mV) generated an outward rectifying instantaneous IV curve similar to the one in A (red squares). <i>C</i>: Repolarizing voltage steps from +40 mV (10 mV increments) reveal tail currents at potentials more negative than -40 mV <i>(left)</i>. <i>Right</i>: IV curve for this cell shows reversal at around -40 mV. Inset: distribution of reversal potentials of I_cs for 8 neurons.</p