T-Type Channel | Control | 3 mM MPS | Wash | |||
---|---|---|---|---|---|---|
V1/2 | k | V1/2 | k | V1/2 | k | |
α1G (0.3 s) | −61.5 ± 1.0 | −5.5 ± 0.1 | −71.0 ± 0.9 | −7.0 ± 0.1 | −64.4 ± 1.8 | −5.9 ± 0.3 |
α1G (30 s) | −73.0 ± 1.2 | −4.0 ± 0.1 | −80.0 ± 1.5 | −4.9 ± 0.1 | −75.7 ± 1.9 | −4.0 ± 0.1 |
α1G (preincubated) | −69.3 ± 1.0 | −4.0 ± 0.1 | −73.5 ± 1.4 | −5.1 ± 0.6 | ||
α1H (5 s) | −71.7 ± 0.2 | −3.7 ± 0.1 | −77.0 ± 0.2 | −4.3 ± 0.2 | −73.2 ± 0.2 | −4.3 ± 0.1 |
α1I (30 s) | −69.1 ± 0.7 | −5.1 ± 0.2 | −75.8 ± 1.5 | −4.4 ± 0.1 | −72.8 ± 1.0 | −4.8 ± 0.1 |
α1I (preincubated) | −63.7 ± 0.4 | −3.8 ± 0.3 | −68.5 ± 2.0 | −3.9 ± 0.3 |
The effects of MPS on the inactivation properties were determined using a double pulse protocol (see Fig. 6). The prepulse duration is shown in parenthesis. Data from each cell were collected before, in the presence of 3 mM MPS, or after washout. The results from each cell were fit with a Boltzmann equation and then averaged. All V 1/2values are in millivolts. Steady-state inactivation curves using 30-s prepulses were also performed on cells that were preincubated (>4 min) in 3 mM MPS before patching the cell and recorded in the continued presence of drug. The double pulse protocol was run 2 min after establishment of the whole cell configuration. As control for these experiments, the protocol was run on other cells a similar time after patching. The V 1/2 and k values for the curves of Fig. 6D were: control, −71.7, −3.8; 10 mM ethosuximide, −76.5, −3.9; wash, −74.0, −3.8; respectively. Charge carrier was 5 mM Ca2+ in α1G and α1I experiments and 10 mM Ba2+in the case of α1H.