TABLE 2.

Parameters for simulation of a hyperpolarization-activated channel for bipolar cells and rod photoreceptors

Element	Value	Reversal potential	Kinetics
Cm membrane capacitance	10 pF	NA	NA
gns nonspecific leakage conductance	0.15 nS	0 mV	ohmic
gKleak voltage-independent K+	0.15 nS	−90 mV	ohmic
gh hyperpolarization-activated	2 nS	−75 mV or −20 mV See*	See*

^*Kinetics for the hyperpolarization-activated channel modified from Barnes and Hille (1989).

For bipolar cells:

α = a₁/(1 + exp((V + b₁)/c₁), a₁ = 0.3 ms⁻¹, b₁ = 98 mV, c₁ = 10 mV

β = a₂/(1 + exp(−(V + b₂)/c₂), a₂ = 0.3 ms⁻¹, b₂ = 30 mV, c₂ = 20 mV

n = α/(α + β), τ = 1 /(α + β)

g = g_h (1−(1 + 3n)(1 − n)³)

Reversal potential, –75 mV

For rod photoreceptors:

α = a₁/(1 + exp((V + b₁)/c₁), a₁ = 0.03 ms⁻¹, b₁ = 98 mV, c₁ = 10 mV

β = a₂/(1 + exp(−(V + b₂)/c₂), a₂ = 0.03 ms⁻¹, b₂ = 30 mV, c₂ = 20 mV

n = α/(α + β), τ = 1/(α + β)

g = g_h (1 − (1 + 3n)(1 − n)³)

Reversal potential, −20 mV