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. 2007 Aug 10;93(10):3421–3433. doi: 10.1529/biophysj.107.110031

TABLE 4.

Model parameters and initial conditions

Symbol parameters Description Units Value Source
kf,1 R1 forward rate constant μM−1 s−1 3.00 × 10−4 (fitted value)*
Kd,1 R1 dissociation constant μM 3.00 × 10−5 Bers (28)
kf,2 R2 forward rate constant μm2 s−1 2.75 × 10−4 Lukas (25)
Kd,2 R2 dissociation constant μm−2 27,500 Lukas (25)
kf,3 R3 forward rate constant μm2 s−1 1.00 Lukas (25)
kr,3 R3 reverse rate constant s−1 1.00 × 10−3 Lukas (25)
kf,4 R4 forward rate constant μM−1 s−1 3.00 × 10−1 (fitted value)†
Kd,4 R4 dissociation constant μM 3.00 × 10−5 Bers (28)
kf,5 R5 forward rate constant s−1 4.00 × 10−4 (fitted value)‡
kf,6 R6 forward rate constant s−1 1.00 Lukas (25)
kf,7 R7 forward rate constant s−1 1.50 × 10−1 Lukas (25)
kf,8 R8 forward rate constant μM−1 s−1 1.67 × 10−2 Lukas (25)
kr,8 R8 reverse rate constant s−1 1.67 × 10−2 Lukas (25)
kf,9 R9 forward rate constant μm2 s−1 4.20 × 10−3 Lukas (25)
kr,9 R9 reverse rate constant s−1 1.00 Lukas (25)
kf,10 R10 forward rate constant μm2 s−1 4.20 × 10−2 Lukas (25)
kr,10 R10 reverse rate constant s−1 1.00 Lukas (25)
kf,11 R11 forward rate constant μM−1 s−1 3.34 × 10−2 See discussion under PLCβ Cycling
Kd,11 R11 dissociation rate constant μM 1.00 × 10−1 Lukas (25)
kf,12 R12 forward rate constant s−1 6.00 Lukas (25)
kf,13 R13 forward rate constant s−1 6.00 See discussion under PLCβ Cycling
kf,14 R14 forward rate constant s−1 4.44 × 10−1 See discussion under IP3 Production and Degradation
Km,14 R14 Km value μM 19.8 Bhalla and Iyengar (49)
kf,15 R15 forward rate constant s−1 3.80 (fitted value)§
Km,15 R15 Km value μM 5.00 Bhalla and Iyengar (49)
kf,16 R16 forward rate constant s−1 1.25 DOQCS1 database (50)
Ls Ligand stimulation concentration μM varies User-defined
PIP2 PIP2 density μm−2 4000 Xu et al. (51)
ts Time of stimulation s varies User-defined
Vc Cytosolic volume μm3 2549.3 Leri et al. (52), Bers (28)
Initial conditions
Ca Cytosolic Ca2+ concentration μM 1.00 × 10−1 Bers (28) (steady state)
Gd GαGDP density μm−2 10,000 Lukas (25) (steady state)
Gt GαGTP density μm−2 0.00 (unstimulated)
IP3 IP3 concentration μM 0.015 See discussion under IP3 Production and Degradation
L Ligand concentration (extracellular) μM 0.00 (unstimulated)
P PLCβ density μm−2 90.9 Lukas (25) (steady state)
Pc PLCβ-Ca2+ density μm−2 9.09 Lukas (25) (steady state)
Pg PLCβ-GαGTP density μm−2 0.00 (unstimulated)
Pcg PLCβ-Ca2+-GαGTP density μm−2 0.00 (unstimulated)
R Noncoupled receptor density μm−2 13.9 Kobayashi (53) (steady state)
Rg Precoupled receptor density μm−2 5.06 Kobayashi (53) (steady state)
Rl Ligand-bound receptor density μm−2 0.00 (unstimulated)
Rlg Active receptor density μm−2 0.00 (unstimulated)
Rlgp Phosphorylated receptor density μm−2 0.00 (unstimulated)
Rpc Plasma membrane/cytosolic volume ratio μm−1 4.61 Bers (28)

All parameters are as at steady state. Fitted values are as a result of refinement to ET-1 data. See footnotes below.

*

Altered from 1.68 × 10−2 (25).

†

Altered from 16.8 (25).

‡

Altered from 3.00 × 10−2 (25).

§

Altered from 48.0 (49).