Table 1. Values for constants in the... | Rockefeller University Press

Table 1.

Values for constants in the model

Parameter	Units	Meaning	Value	Source
J_xce	µmol/s	Maximum Ca²⁺ efflux from cell via pmCa pump	0.28 v_c/b_c
K_ce	µM	Half saturation Z-value for pmCa pump	0.425
A₁	µmol/s	Constant Ca²⁺ leak into cell	0.0015 v_c/b_c
A₂	/s	Ca²⁺ flux into cell per unit of IP₃	0.01/b_c
P	µM	IP₃ concentration in cytoplasm	0.7
J_xsi	µmol/s	Maximum SERCA flux	9 v_c/b_c
K_si	µM	Half saturation Z-value for SERCA pump	0.1
k_se	L/s	Constant Ca²⁺ leak from store	3.3v_c/b_c
k_f	L/s	Scale for IP₃-dependent store Ca²⁺ efflux	4.8v_c/b_c
k_p1	/µmol/s	IP₃R binding constant	400	3
k_p2	/µmol/s	IP₃R binding constant	0.2	3
k_p3	/µmol/s	IP₃R binding constant	400	3
k_p4	/µmol/s	IP₃R binding constant	0.2	3
k_p5	/µmol/s	IP₃R binding constant	20	3
k_m1	/s	IP₃R binding constant	52	3
k_m2	/s	IP₃R binding constant	0.21	3
k_m3	/s	IP₃R binding constant	377.2	3
k_m4	/s	IP₃R binding constant	0.029	3
k_m5	/s	IP₃R binding constant	1.64	3
b_c	-	Ca²⁺ buffering constant	0.01	2
v_c	L	Cytosol volume	10⁻¹²	2
v_s	L	Store volume	v_c/5.5	3
C_m	pF	Cell capacitance	25	2
E_i	mV	Reversal potential, passive channels	−67.2	1
E_C	mV	Reversal potential for Ano1 current	−20	1
E_L	mV	Reversal potential for L-type channels	+20	1
G_i	nS	Conductance of passive channels	0.4
G_xC	nS	Max. Ca²⁺-induced Cl⁻ conductance	0.8
G_L	nS	Conductance of L-type Ca²⁺ channels	1.7
K_C	μM	Half saturation for Cl⁻ conductance	1.1
q	-	Hill exponent for Cl⁻ conductance	4	1
V_hm	mV	Half saturation for gate fn. m(V)	−46
V_km	mV	Inverse slope const., gate fn. m(V)	−4
K_h	µM	Half saturation for gate fn. h_∞(Z)	4
ψ	-	Hill exponent for h_∞(Z)	20	1
V_hh	mV	Half saturation for gate fn. h_∞(V)	−48
V_kh	mV	Inverse slope const., gate fn. h_∞(V)	1
τ_n	s	Minimum of time constant τ_h(V)	0.5
τ_x	s	Maximum of time constant τ_h(V)	10
α	(µmol/s)/pA	Ca²⁺ flux per unit current	5.18 × 10⁻¹²	4
z	-	Valency of calcium ion	2	4
F	pC/µmol	Faraday constant	9.6485 × 10¹⁰	4

Parameter	Units	Meaning	Value	Source
J_xce	µmol/s	Maximum Ca²⁺ efflux from cell via pmCa pump	0.28 v_c/b_c
K_ce	µM	Half saturation Z-value for pmCa pump	0.425
A₁	µmol/s	Constant Ca²⁺ leak into cell	0.0015 v_c/b_c
A₂	/s	Ca²⁺ flux into cell per unit of IP₃	0.01/b_c
P	µM	IP₃ concentration in cytoplasm	0.7
J_xsi	µmol/s	Maximum SERCA flux	9 v_c/b_c
K_si	µM	Half saturation Z-value for SERCA pump	0.1
k_se	L/s	Constant Ca²⁺ leak from store	3.3v_c/b_c
k_f	L/s	Scale for IP₃-dependent store Ca²⁺ efflux	4.8v_c/b_c
k_p1	/µmol/s	IP₃R binding constant	400	3
k_p2	/µmol/s	IP₃R binding constant	0.2	3
k_p3	/µmol/s	IP₃R binding constant	400	3
k_p4	/µmol/s	IP₃R binding constant	0.2	3
k_p5	/µmol/s	IP₃R binding constant	20	3
k_m1	/s	IP₃R binding constant	52	3
k_m2	/s	IP₃R binding constant	0.21	3
k_m3	/s	IP₃R binding constant	377.2	3
k_m4	/s	IP₃R binding constant	0.029	3
k_m5	/s	IP₃R binding constant	1.64	3
b_c	-	Ca²⁺ buffering constant	0.01	2
v_c	L	Cytosol volume	10⁻¹²	2
v_s	L	Store volume	v_c/5.5	3
C_m	pF	Cell capacitance	25	2
E_i	mV	Reversal potential, passive channels	−67.2	1
E_C	mV	Reversal potential for Ano1 current	−20	1
E_L	mV	Reversal potential for L-type channels	+20	1
G_i	nS	Conductance of passive channels	0.4
G_xC	nS	Max. Ca²⁺-induced Cl⁻ conductance	0.8
G_L	nS	Conductance of L-type Ca²⁺ channels	1.7
K_C	μM	Half saturation for Cl⁻ conductance	1.1
q	-	Hill exponent for Cl⁻ conductance	4	1
V_hm	mV	Half saturation for gate fn. m(V)	−46
V_km	mV	Inverse slope const., gate fn. m(V)	−4
K_h	µM	Half saturation for gate fn. h_∞(Z)	4
ψ	-	Hill exponent for h_∞(Z)	20	1
V_hh	mV	Half saturation for gate fn. h_∞(V)	−48
V_kh	mV	Inverse slope const., gate fn. h_∞(V)	1
τ_n	s	Minimum of time constant τ_h(V)	0.5
τ_x	s	Maximum of time constant τ_h(V)	10
α	(µmol/s)/pA	Ca²⁺ flux per unit current	5.18 × 10⁻¹²	4
z	-	Valency of calcium ion	2	4
F	pC/µmol	Faraday constant	9.6485 × 10¹⁰	4

Sources (otherwise, estimated): 1 is Imtiaz et al. (2007), although in many cases the values have been reinterpreted in terms of units, etc., 2 is Lees-Green et al. (2014), 3 is Keener and Sneyd (2009), and 4 is a universal physical constant. Estimated values were based on existing sources. L, litre.

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