Figure 7. CRP changed voltage dependence of I_h activation in IB4⁻ Aδ type neuron, but not the reversal potential.

(a) Reversal potential of I_h from control (middle panel) and CRP IB4⁻ Aδ type neurons (lower panel) were achieved by first applying a prepulse to −120 mV to fully activate I_h and then examining the tail currents after repolarization to test potentials from −110 to −50 mV (upper panel). Tail currents were plotted against test potentials. (b) No difference of reversal potential of I_h current was shown between control (black) and CRP (red) group. (c) The activation curve of I_h from control (upper panel) and CRP IB4⁻ Aδ neurons (lower panel) was constructed by measuring tail currents at −120 mV after application of prepulse potentials between −50 to −120 mV (middle inset) and fitted with a Boltzmann equation. (d) The midpoint (V_1/2) for activation of I_h in the CRP IB4⁻ Aδ neurons (red) was shifted 11 mV in the depolarizing direction compared to control neurons (black). (e) The difference of V_1/2 for activation of I_h between two groups was significant. All data are expressed as mean ± S.E.M. *P < 0.05 as compared to control rats.