Model parameters
| Description | Units | Symbol | Value | Reference |
| Cytosolic pH | pHC | 7.2 | Roos and Boron, 1981; Wu et al., 2000 | |
| Cytosolic potassium concentration | mM | [K+]C | 145 | Alberts et al., 2008 |
| Cytosolic sodium concentration | mM | [Na+]C | 10 | Alberts et al., 2008 |
| Cytosolic chloride concentration | mM | [Cl–]C | 5–50 | Sonawane et al., 2002; Alberts et al., 2008 |
| Luminal pH (initial) | pHL | 7.4 | Alberts et al., 2008 a | |
| Luminal potassium concentration (initial) | mM | [K+]L | 5 | Alberts et al., 2008 a |
| Luminal sodium concentration (initial) | mM | [Na+]L | 145 | Alberts et al., 2008 a |
| Luminal chloride concentration (initial) | mM | [Cl–]L | 110 | Alberts et al., 2008 a |
| Proton permeabilityb | cm/s | PH+ | 6 × 105 | |
| Potassium permeability | cm/s | PK+ | 7.1 × 107 | Hartmann and Verkman, 1990 |
| Sodium permeability | cm/s | PNa+ | 9.6 × 107 | Hartmann and Verkman, 1990 |
| Chloride permeability | cm/s | PCl− | 1.2 × 105 | Hartmann and Verkman, 1990 |
| Bilayer capacitance | µF/cm2 | C0 | 1 | Hille, 2001 |
| Lysosome diameter | µm | 0.68 | Van Dyke, 1993 | |
| Lysosome volumec | L | V | 1.65 × 1016 | |
| Lysosome surface areac | cm2 | S | 1.45 × 108 | |
| Buffering capacityd | mM/pH | β | 40 | |
| Osmotic coefficient | ϕ | 0.73 | Kielland, 1937 | |
| Water permeability | cm/s | PW | 0.052 | Lencer et al., 1990 |
| Partial molar volume of water | cm3/mol | νW | 18 | Verkman, 2000 |
| Cytoplasmic osmolyte concentratione | mM | ΦC | 290 |
| Description | Units | Symbol | Value | Reference |
| Cytosolic pH | pHC | 7.2 | Roos and Boron, 1981; Wu et al., 2000 | |
| Cytosolic potassium concentration | mM | [K+]C | 145 | Alberts et al., 2008 |
| Cytosolic sodium concentration | mM | [Na+]C | 10 | Alberts et al., 2008 |
| Cytosolic chloride concentration | mM | [Cl–]C | 5–50 | Sonawane et al., 2002; Alberts et al., 2008 |
| Luminal pH (initial) | pHL | 7.4 | Alberts et al., 2008 a | |
| Luminal potassium concentration (initial) | mM | [K+]L | 5 | Alberts et al., 2008 a |
| Luminal sodium concentration (initial) | mM | [Na+]L | 145 | Alberts et al., 2008 a |
| Luminal chloride concentration (initial) | mM | [Cl–]L | 110 | Alberts et al., 2008 a |
| Proton permeabilityb | cm/s | PH+ | 6 × 105 | |
| Potassium permeability | cm/s | PK+ | 7.1 × 107 | Hartmann and Verkman, 1990 |
| Sodium permeability | cm/s | PNa+ | 9.6 × 107 | Hartmann and Verkman, 1990 |
| Chloride permeability | cm/s | PCl− | 1.2 × 105 | Hartmann and Verkman, 1990 |
| Bilayer capacitance | µF/cm2 | C0 | 1 | Hille, 2001 |
| Lysosome diameter | µm | 0.68 | Van Dyke, 1993 | |
| Lysosome volumec | L | V | 1.65 × 1016 | |
| Lysosome surface areac | cm2 | S | 1.45 × 108 | |
| Buffering capacityd | mM/pH | β | 40 | |
| Osmotic coefficient | ϕ | 0.73 | Kielland, 1937 | |
| Water permeability | cm/s | PW | 0.052 | Lencer et al., 1990 |
| Partial molar volume of water | cm3/mol | νW | 18 | Verkman, 2000 |
| Cytoplasmic osmolyte concentratione | mM | ΦC | 290 |
These are typical extracellular values. Values in nascent lysosomes are not known.
This value was estimated based on fits to data in Fig. 2 A. An experimental estimate based on measurements from rat liver lysosomes is 2.9 × 10−4 cm/s (Van Dyke, 1993).
These values are calculated for a sphere of diameter 0.68 µm.
Buffering capacity varies with the pHL. An earlier study reported a value of 60 mM/pH at pHL 6.8, which gradually decreased to 20 mM/pH at pHL 5.2 (Van Dyke, 1993). A recent study reports a value of 61.5 mM/pH for pHL 4.5–5.0 (Steinberg et al., 2010). We use a constant buffering capacity that falls in between these reported values and gives a best fit value to the in vitro data in Fig. 2 A.
290 mM was a typical value, which was adjusted to maintain initial osmotic equilibrium.