TABLE I.
Composition of Internal Solutions
Cs Glutamatea or K2SO4 b | CaT | [Ca2+] | MgT | [Mg2+] | ||
---|---|---|---|---|---|---|
mM | mM | nM | mM | mM | ||
Frog | Varied [Ca2+] | 100 | 0.177 | 100 | 4.51 | 0.3 |
100 | 0.304 | 200 | 4.51 | 0.3 | ||
100 | 0.474 | 400 | 4.51 | 0.3 | ||
100 | 0.659 | 800 | 4.51 | 0.3 | ||
Varied [Mg2+] | 100 | 0.177 | 100 | 4.96 | 0.4 | |
100 | 0.176 | 100 | 5.34 | 0.5 | ||
100 | 0.174 | 100 | 6.24 | 0.8 | ||
100 | 0.172 | 100 | 7.84 | 1.45 | ||
Rat | Varied [Ca2+] | 80 | 0.178 | 100 | 9.80 | 2.0 |
80 | 0.306 | 200 | 9.79 | 2.0 | ||
80 | 0.403 | 300 | 9.78 | 2.0 | ||
80 | 0.443 | 350 | 9.78 | 2.0 | ||
80 | 0.479 | 400 | 9.78 | 2.0 | ||
Varied [Mg2+] | 80 | 0.189 | 100 | 3.99 | 0.2 | |
80 | 0.186 | 100 | 5.53 | 0.5 | ||
80 | 0.183 | 100 | 7.13 | 1.0 | ||
73 | 0.168 | 100 | 14.3 | 4.0 | ||
60 | 0.146 | 100 | 25.2 | 10.0 | ||
28 | 0.091 | 100 | 59.8 | 40.0 |
All internal solutions contained (in mM) HEPES or trismaleate (10), EGTA (1), phosphocreatine (5), ATP (5), glucose (10), dextran 8% and Fluo-4 (0.1). ATP was added as Mg salt up to 5 mM. When low Mg was required, the difference to 5 mM was replaced by the Na salt. pH was adjusted to 7 using CsOH, and osmolality to 265 mOsm/kg for frog or 320 mOsm/kg for rat, using cesium glutamate or potassium sulfate (for frog or rat) or water as needed.
Frog.
Rat.