Figure 1.

Hyperpolarizing-activated inward current (I_h) recording in dorsal root ganglion neurones. (a) Hyperpolarizing voltage commands elicited an initial current, referred to as the instantaneous currents (I_in, triangle) proceeded by a steep capacity current and followed by the development of a slow inward current reaching a steady-state level at the end of the voltage command (I_ss, square). (b) I_in, I_h (circle) and I_ss are plotted as a function of membrane potential. The amplitude of I_h was given as difference of the slow inward and instantaneous currents (I_h=I_ss−I_in). The data were fitted by eye. (c) Activation curves of I_h current. Whole-cell recordings from de- and hyperpolarization-activated currents evoked from −80 mV to different test potentials. Tail-current relaxations are indicated by arrows and are shown at higher resolution in the lower sets of traces. (d) Normalized peak relaxation currents were fitted with the Boltzmann equation: 1/(1+exp(−(E−E₅₀)/k)).