NEURON Note #23


Goals: Compare Altomare's HCN1 and HCN2 Models


Introduction:

CA1 pyramidal neurons express both HCN1 and HCN2 proteins in their dendrites. Thus, the characteristics of native Ih are between those of HCN1 and HCN2. This note examines the properties of Altomare's HCN1 and HCN2 models (2001). Compared to native Ih, HCN2 is much slower and has a hyperpolarized GV curve. Therefore, HCN1 might be dominant in determing the characteristics of native Ih and HCN2 plays a regulatory role.


Methods:

Software

Q10 is 4.5. Temperature = 33.


Results:

No Ih HCN1 HCN2
gbar_h (S/cm2) 0 2.2e-5 2.2e-5
e_pas (mV) -65 -75 -65.1
Time Constant (ms) 30.0 22.4 29.7
Imput Resistance (MΩ) 95.5 50.2  93.4
Rebound Slope (mV/mV) 0.00 -0.13 -0.00
Temporal Summation (%) 43.7 2.1 42.8
Depolarizing Resonance Frequency (Hz) 0.6 4.6 0.6
Hyperpolarizing Resonance Frequency (Hz) 1.1 4.8 1.1
Biophysical Properties      
Vhalf (mV)   -68.9 -98.0
k (mV)   9.4 6.0
Activation Tau at -65 mV (ms)   41.4 3185.0
Deactivation Tau at -65 mV (ms)   38.7 122.5

Impdedance Magnitude

Impedance Magnitude

Voltage Lag

Voltage Lag

GV Curve

GV Curve

Time Constant

Time Constant Time Constant