Table 1.

Commonly used abbreviations and parameters

Abbreviation Definition 
Kv Voltage-dependent K+ channel (for example, Shaker) 
C, O Closed and open conducting states of the pore (L) 
R, A Resting and activated states of the voltage sensor (J) 
F, B Free and bound ligand states of the Ca2+ sensor (K) 
Φ System energy—equal to the chemical potential of the channel 
U, H, G Other thermodynamic potentials (energy, enthalpy, Gibbs) 
T, P, V, μ Intensive variables (temperature, pressure, voltage, chemical potential) 
S, V, Q, N Extensive variables (entropy, volume, charge, species number) 
kT, RT Boltzmann or gas constant times temperature 
i, I Ionic current (single channel, whole patch) 
ig, Ig Gating current (single channel, whole patch) 
g, G Conductance (single channel, whole patch) 
G-V, Q-V Equilibrium curves as a function of V (conductance, charge) 
g〉, 〈q〉, 〈n〉 Averaged single-channel quantities (conductance, charge, ligand number) 
Gmax, gmax Maximum conductance (single channel, whole patch) 
Qmax Total gating charge displacement (whole patch) 
N Number of channels in a patch 
Z Channel partition function 
ZK Z/∂K 
η Particle potential—the transition energy of a particle 
J, K, L, P Equilibrium constants for particles J, K, L, and P 
B, C, D, E, F, G Allosteric (coupling) factors 
ΔH, ΔG Particle transition energies (enthalpy, Gibbs energy) 
Δq, Δn, ΔS Particle displacements (gating charge, ligand number, entropy) 
ΔqT, ΔnT Total displacement per channel (gating charge, ligand number) 
WA Work function of the principal component A 
FB External force activating a secondary component B 
WL, Wq Specific work functions (pore opening, gating charge displacement) 
WH[g] Conductance Hill energy (= −WL
WC[q] Electrical capacitance energy (= −Wq
VM Mean (also called “median”) voltage of activation (= −WC[q]qT
V1/2 Half-activation voltage 
μm Mean (or “median”) ligand activity 
Cq, CP Capacitance (electrical, heat) 
fq Normalized gating charge capacitance (= Cq/N
m Ramp speed (mV/ms) or slope of linkage plot asymptote (contextual) 
N, Veq, gleak, Cpatch Patch parameters (channel number, equilibrium potential, leak conductance, patch capacitance) 
fs, fc Sampling frequency, cutoff frequency 
α, β Rate constants (forward, backward) 
PO Open probability (= G/Gmax
qa〉 Mean activation charge displacement (= kTdlnPO/dV
B Boltzmann equation (= J/(1 + J), with J = exp(ΔqB(VV1/2)/kT)) 
H Hill equation (= KnH/(1 + KnH), where nH is the Hill coefficient 
Abbreviation Definition 
Kv Voltage-dependent K+ channel (for example, Shaker) 
C, O Closed and open conducting states of the pore (L) 
R, A Resting and activated states of the voltage sensor (J) 
F, B Free and bound ligand states of the Ca2+ sensor (K) 
Φ System energy—equal to the chemical potential of the channel 
U, H, G Other thermodynamic potentials (energy, enthalpy, Gibbs) 
T, P, V, μ Intensive variables (temperature, pressure, voltage, chemical potential) 
S, V, Q, N Extensive variables (entropy, volume, charge, species number) 
kT, RT Boltzmann or gas constant times temperature 
i, I Ionic current (single channel, whole patch) 
ig, Ig Gating current (single channel, whole patch) 
g, G Conductance (single channel, whole patch) 
G-V, Q-V Equilibrium curves as a function of V (conductance, charge) 
g〉, 〈q〉, 〈n〉 Averaged single-channel quantities (conductance, charge, ligand number) 
Gmax, gmax Maximum conductance (single channel, whole patch) 
Qmax Total gating charge displacement (whole patch) 
N Number of channels in a patch 
Z Channel partition function 
ZK Z/∂K 
η Particle potential—the transition energy of a particle 
J, K, L, P Equilibrium constants for particles J, K, L, and P 
B, C, D, E, F, G Allosteric (coupling) factors 
ΔH, ΔG Particle transition energies (enthalpy, Gibbs energy) 
Δq, Δn, ΔS Particle displacements (gating charge, ligand number, entropy) 
ΔqT, ΔnT Total displacement per channel (gating charge, ligand number) 
WA Work function of the principal component A 
FB External force activating a secondary component B 
WL, Wq Specific work functions (pore opening, gating charge displacement) 
WH[g] Conductance Hill energy (= −WL
WC[q] Electrical capacitance energy (= −Wq
VM Mean (also called “median”) voltage of activation (= −WC[q]qT
V1/2 Half-activation voltage 
μm Mean (or “median”) ligand activity 
Cq, CP Capacitance (electrical, heat) 
fq Normalized gating charge capacitance (= Cq/N
m Ramp speed (mV/ms) or slope of linkage plot asymptote (contextual) 
N, Veq, gleak, Cpatch Patch parameters (channel number, equilibrium potential, leak conductance, patch capacitance) 
fs, fc Sampling frequency, cutoff frequency 
α, β Rate constants (forward, backward) 
PO Open probability (= G/Gmax
qa〉 Mean activation charge displacement (= kTdlnPO/dV
B Boltzmann equation (= J/(1 + J), with J = exp(ΔqB(VV1/2)/kT)) 
H Hill equation (= KnH/(1 + KnH), where nH is the Hill coefficient 

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