Table 1.
Parameters used in the simulations
| Parameter | Value | Reference |
|---|---|---|
| Myocyte volume1 | 46289 × 10−12 cm3 | This paper |
| Myocyte surface area/volume ratio | 2017 cm−1 | This paper |
| Non-ionized acetate permeability (PHA) 2 | 0.12 cm s−1 | Stein, 1986 |
| Ionized acetate permeability (PA−) 3 | 6.77 × 10−8 cm s−1 | See legend |
| CO2 permeability | 0.58 cm s−1 | Forster, 1969 |
| Ionization constant of acetate | 10 −4.528 | Harned & Hickey, 1937 |
| Equilibrium constant of CO2 reaction | 10−6.12 | This paper |
1
Assume cylindrical shape; myocyte diameter, 21.5 ± 0.7 μm (mean ±s.e.m., n= 33); length, 127.5 ± 3.3 μm (mean ±s.e.m., n= 33).
2
Calculated value from the equation PHA=KHADHA/δ, where KHA (partition coefficient) = 0.49, DHA (diffusion constant) = 2.51 × 10−7 cm2 s−1, and δ (membrane thickness) = 100 × 10−8 cm).
3
We calculated this value on the assumption that acetate ion current is 50 pA at a resting membrane potential of -80 mV (this is an arbitrary current value, chosen to be of an acceptable amplitude for a whole-cell anion current with a driving force of 50-100 mV) and [A−]i and [A−]o are 0.03 and 0.08 m, respectively.