Hyperpolarization-activated cyclic nucleotide-gated cation channel subtypes differentially modulate the excitability of murine small intestinal afferents

Figure 4 I_h steady-state parameters and activation kinetics in DiI-labeled DRG and NG neurons. A: I_h current-voltage relationship between DiI-labeled dissociated dorsal root ganglia (DRG) and nodose ganglia neurons (NG); B: I_h current density-voltage relationship between DiI-labeled DRG and NG neurons; C: The time constant of I_h current. I_h current traces were fitted with two exponentials according to the following equation: I_h(t) = Af exp(-t/τf) + As exp(-t/τs), where I_h(t) is the amplitude of the current at time t and Af and As are the initial amplitudes of the fast (τf) and slow (τs) activation time constant components, respectively. Time constants were obtained by fitting currents using pCLAMP; D: I_h current activation curves. Normalized activation curves were obtained from tail currents at -80 mV and fitted by Boltzmann function: I_h/I_h(max) =1/{1+ exp[(Vm – V_1/2)/k]}, where I_h is the peak amplitude of the tail current recorded immediately after the pre-pulse, I_h(max) is the maximal current recorded after the maximal prepulse of -120 mV, V_m is the membrane potential, V_1/2 is the membrane potential at which I_h conductance is half-activated, and k is a slope factor of the curve. Data were expressed as mean ± SE. ^aP < 0.05 vs DiI-labeled DRG neurons.