Table 2
Model parameters
| Parameter | Value | Notes |
|---|---|---|
| [Ca2+]rest | 45 nm | Airaksinen et al. (1997) |
| [Mg2+]i | 590 μm | Calculated, held constant |
| Ca2+ influx | ||
| Peak amplitude | 36–130 pA | |
| Half-width | 4 ms | |
| Extrusion | ||
| Michaelis–Menten constant, Km | 3 μm | |
| Max. pump velocity dendrite, vmax | 30–300 pmol cm−2 s−1 | |
| Oregon Green BAPTA-1 | ||
| Effective concentration | 160 μm | 80% of pipette conc. |
| KD | 325 nM | This study |
| Koff | 140 s−1 | Eberhard & Erne (1991)* |
| Kon | 0.43 × 109 M−1 s−1 | Calculated |
| Calbindin D28k | ||
| Effective concentration | 40 μm | Maeda et al. (1999)† |
| Binding sites (non-cooperative) | 4 | Nägerl et al. (2000) |
| Ratio of high- and medium-affinity binding sites | 2:2 | Näet al. (2000) |
| Koff,medium aff. | 35.8 S−1 | Näet al. (2000) |
| Koff, high aff. | 2.6 s−1 | Nägerl et al. (2000) |
| Kon, medium aff. | 4.35 × 107 M−1 s−1 | Nägerl et al. (2000)‡ |
| Kon, high aff. | 0.55 × 107m−1 s−1 | Nägerl et al. (2000)‡ |
| KD, medium aff. | 822nm | Calculated |
| KD, high aff. | 474 nm | Calculated |
| Parvalbumin | ||
| Effective concentration | 40 μm | Kosaka et al. (1993)§ |
| Binding sites (non-cooperative) | 2 | |
| Koff,Ca | 0.95 S−1 | Lee et al. (200b) |
| Koff,Mg | 25 s−1 | Lee et al. (200b) |
| KD,Ca | 9 nm | Lee et al. (2000b) |
| KD,Mg | 31 μm | Eberhard & Erne (1994) |
| Kon,Ca | 10.7 × 107m−1 s−1 | Calculated |
| Kon,Mg | 0.8 × 106m−1 s−1 | Calculated |
| Geometry | ||
| Volume of spine head | 0.1 μm3 | Harris & Stevens (1988) |
| Surface area of spine head | 0.9 μm2 | Harris & Stevens (1988) |
| Radius of spine neck | 0.1 μm | Harris & Stevens (1988) |
| Length of spine neck | 0.66 μm | Harris & Stevens (1988) |
| Spine density | 3.4 μm−1 | Vecellio et al. (200) |
| Radius of dendritic segment | 1 μm | |
| Length of dendritic segment | ||
| Single-compartment model | 10 μm | |
| Double-compartment model | 0.3 μm | Calculated |
| Diffusional mobility | ||
| DCa | 223 μm2 s−1 | Allbritton et al. (1992) |
| DOGB | 15 μm2 s−1 | Holthoff et al. (2002)* |
| DPV | 43 μm2 s−1 | Schmidt et al. (2003) |
| DCB | 28 μm2 s−1 | Schmidt et al.‖ |
| Fraction of immobile calbindin | 0.2 | Schmidt et al.‖ |
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↵* Data for Calcium Green-1, an indicator dye closely related to OGB-1
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↵† assuming that their fast buffer is CB, that 33% of CB is occupied by MG2+ and that 25% of CB is wahsed out during out wholecell recordings
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↵‡ assuming two-fold slower kinetics in the dendrites compared with the in vitro data (Berggård et al. 2002)
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↵§ assuming 50 % washout of PV during our recordings.
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↵‖ H. Schmidt, B. Schwaller & J. Eilers, unpublished observations.