Table 2.
Frequencies of direct transitions
| Between shut level and open levels | Between open channel current levels | ||||
|---|---|---|---|---|---|
| Patch type | High & Low conductance | Only High conductance | High & Low conductance | Only High conductance | |
| Sequence (pS) | (patches = 6) (%) | (patches = 7) (%) | Sequence (pS) | (patches = 6) (%) | (patches = 7) (%) |
| 0–17 | 4.03 ± 0.95 (1391) | — | 17–42 | 0.74 ± 0.27 (255) | — |
| 17–0 | 4.93 ± 1.26 (1696) | — | 42–17 | 1.33 ± 0.50 (455) | — |
| 0–33 | 1.10 ± 0.21 (248) | — | 33–42 | 0.40 ± 0.18 (85) | — |
| 33–0 | 1.17 ± 0.24 (277) | — | 42–33 | 0.47 ± 0.18 (106) | — |
| 0–42 | 17.01 ± 2.20 (5460) | 5.09 ± 1.19 (955) | 33–49 | 0.60 ± 0.23 (147) | — |
| 42–0 | 16.58 ± 2.00 (5295) | 5.15 ± 1.24 (986) | 49–33 | 0.66 ± 0.28 (157) | — |
| 0–49 | 23.03 ± 2.89 (5954) | 40.05 ± 1.32 (7029) | 42–49 | 2.37 ± 0.43 (644) | 4.66 ± 0.63 (861) |
| 49–0 | 23.27 ± 2.96 (5991) | 40.47 ± 1.36 (7096) | 49–42 | 2.32 ± 0.38 (624) | 4.59 ± 0.63 (860) |
| Sub-totals | 91.12 % | 90.76 % | Sub-totals | 8.89 % | 9.25 % |
| N | (26312) | (16066) | N | (2473) | (1721) |
The percentage of all direct transitions between current levels (shown as means ± s.e.m) and the total number of each class of transition is given for patches where both high and low conductance channels were evident, or where only high conductance channels were observed. Direct transitions between open current levels were identified as events where both open levels were greater than 2.5 Tr = 415 μs in duration and no gap longer than the shut time resolution (50 μs) was detected between the two levels. Openings were allocated to each of the four different conductance levels using Acrit values calculated from the amplitude distribution as described in Methods. For patches where both high and low conductance channels were observed, there are 12 possible ways four different open channel current levels can be connected in pairs. Only eight of these combinations are presented as no direct transitions were detected between 17 and 33 pS levels or between 17 and 49 pS levels.