Solution | Free [Mg2+] (mm) | MgCl2 (mm) | Free [Ca2+] (nm) | CaCl2 (mm) | EGTA (mm) | EDTA (mm) | BAPTA (mm) | KCl (mm) |
---|---|---|---|---|---|---|---|---|
I | 0.01 | 0.14 | 25 | 0.89 | 5 | 0.2 | 2 | 121.2 |
II | 0.1 | 0.13 | 25 | 0.86 | 5 | 0 | 2 | 121 |
III | 1 | 1.26 | 25 | 0.83 | 5 | 0 | 2 | 119.3 |
IV | 5 | 6.1 | 25 | 0.72 | 5 | 0 | 2 | 112.2 |
V | 10 | 12 | 25 | 0.62 | 5 | 0 | 2 | 103.5 |
VI | 10 | 12 | 0 | 0 | 5 | 0 | 10 | 100.4 |
Concentrations of free Mg2+ and Ca2+ were calculated using Maxchelator software (see Materials and Methods). In addition to the components indicated, each solution contained (in mm) the following: 10 NaAsp, 5 tetraethylammonium, 5 HEPES. Differences in osmolarity were compensated for with different concentrations of KCl, and solutions were titrated to pH 7.2 with KOH.