Table 3 Parameters used to model ion transport across the sarcolemmal membrane

F

Faraday's constant

96485 coul · mol^-1

--

R

Ideal gas constant

8314 mJ · mol^-1 · K^-1

--

T

Absolute temperature

290 K

Measured

[Ca²⁺] _o

Extracellular Ca²⁺ concentration

1.0 mM

Measured

[Na⁺] _o

Extracellular Na⁺ concentration

140.0 mM

Measured

[Cs⁺] _o

Extracellular Cs⁺ concentration

3.0 mM

Measured

Z _Na , Z _Cs

Valence of Na⁺ and Cs⁺ ions

1.0

--

Z _Ca , Z _Ba

Valence of Ca²⁺ and Ba²⁺ ions

2.0

--

P _Ca

Permeability of L-Type calcium channel to Ca²⁺

6.7367 × 10^-9 μL · s^-1

[30]*

P _Na

Permeability of L-Type calcium channel to Na⁺

8.0355 × 10^-11 μL · s^-1

[30]*

P _Cs

Permeability of L-Type calcium channel to Cs⁺

6.2088 × 10^-11 μL · s^-1

[30]*

K _mAllo

Dissociation constant for allosteric Ca²⁺ activation

125 × 10^-6 mM

[85]*

K _mCao

Dissociation constant for extracellular Ca²⁺

1.14 mM

[85]*

K _mCai

Dissociation constant for intracellular Ca²⁺

0.0036 mM

[122]*

K _mNao

Dissociation constant for extracellular Na⁺

87.5 mM

[83]*

K _mNai

Dissociation constant for intracellular Na⁺

12.3 mM

[85]*

V _max

Maximum Na⁺/Ca⁺ exchange current

776.2392 pA

[85]*

k _mpca

Half saturation constant for the SL Ca²⁺ pump

0.5 μM

[30]*

${\overline{I}}_{PMCA}$

Maximum sarcolemmal Ca²⁺ pump current

1.15 pA

[30]*

K _mcs

Dissociation constant for extracellular Cs⁺

1.5 × 10³ μM

[94, 92, 88, 74]^‡

K _mna

Dissociation constant for intracellular Na⁺

2.14 × 10⁵ μM

[94, 92, 88, 74]^‡

${\overline{I}}_{NaCs}$

Maximum Na⁺/Cs⁺ pump current

147.3 pA

[94, 92, 88, 74]^‡

G _Nab

Maximum background Na⁺ current conductance

0.00141 nS

[30]*

R _a

Mean access resistance of the tubular system

20.0 kΩ

[123]*