Figure 3.

Voltage responses to current stimulus protocols. (A) Typical voltage responses to current stimulus for (i) activation and (ii) inactivation of the low-threshold conductance. Blockade of PIR response by Co²⁺ (iii), demonstrates the Ca²⁺ dependence of the PIR response. (B) (i) Experimental protocol for determination of the activation parameter consisted of 500 ms step pulses of increasing current amplitude. The holding current was adjusted such that the membrane potential was at −80 mV at the start of the step pulse. (ii) Protocol for determination of the inactivation parameter consisted of hyperpolarizing current steps of increasing amplitude and of 500 ms duration. The holding current at the start of the step pulses is adjusted such that the membrane potential is at −45 mV.