Table 1

Model parameters and initial conditions

Parameter

Value

Source

Meaning of the parameter


kins

10-3 nM-1 s-1

[36]

insulin binding to the receptor

kins1d

4·10-4 s-1

[36]

insulin dissociation from the receptor (I1, PM)

kins2d

4·10-2 s-1

[36]

insulin dissociation from the receptor (I2, PM)

kins1den

1.925·10-3 s-1

[49]

insulin dissociation from the receptor (I1, EN)

kins2den

3.85·10-3 s-1

[50]

insulin dissociation from the receptor (I2, EN)

kyd

3.85·10-3 s-1

[51]

receptor dephosphorylation (PM)

kyden

7.22·10-3 s-1

[52]

receptor dephosphorylation (EN)

kyp

0.0231 s-1

[52]

autophosphorylation of the receptor (I1 and I2)

intk1

5.5·10-4 s-1

[34]

internalization of phosphorylated receptors

intk2

2·10-4 s-1

[34]

internalization of unphosphorylated receptors

reck1

1.533·10-3 s-1

[34]

recycling of receptors without insulin

k1ub

0.35 s-1

[46]

nonspecific insulin binding in the liver

k2ub

0.2 s-1

[46]

dissociation of nonspecifically bound insulin

pansec

0.0016976 nM·s-1

calc.

pancreatic insulin secretion

K pan

0.5 nM

ass.

concentration of half-maximal insulin secretion

mliver

0.05·mbody

[46]

mass of the liver

vp

0.03375·10-3 l·g-1·mbody

[54]

plasma volume

ρliver

1.051·103 l-1

[53]

density of the liver

vhep

(mliver/ρliver)·0.78

[45]

total hepatocyte volume

vd

0.272·10-3 l·g-1·vhep·ρliver

[46]

volume of the space of Disse

mkidney

2·0.85 g·mbody/(230 g)

[55]

mass of the kidney

K kidney

0.0225·10-3 l·(s·g)-1·mkidney

[47]

clearance of the kidney


Note that mbody (body weight in g), tin (injection time in s), nin and n*,in (amounts of injected unlabeled and labeled insulin in nmol) are also model parameters. We do not give values for them in this table as they depend on the analyzed scenario. Note that the model can be used for rats of arbitrary body weights as well as for different injection times and amounts of injected labeled and unlabeled insulin. Initial conditions are: Ins = 0.07, Ins* = 0, R = 31.619, IR = 0.430007, I2R = 0.000696311, Rp = 0.227528, IRp = 2.07275, I2Rp = 0.00363012, Ren = 4.88528, IRen = 0.145537, I2Ren = 0.000121295, Rpen = 0.122602, IRpen = 0.492464, I2Rpen = 0.000433466, Insub = 1.29948·10-6·mbody, Ins*,ub = 0. The unit of Insub and Ins*,ub is nmol, the unit of all other state variables is nM. ass.: assumption, calc.: calculation (see Additional file 4), EN: in endosomes, PM: at the plasma membrane, I1: one insulin molecule bound to the receptor, I2: two insulin molecules bound to the receptor.

Koschorreck and Gilles BMC Systems Biology 2008 2:43   doi:10.1186/1752-0509-2-43

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