Table 1.
Comparative data measured for If in freshly isolated cells and in the three types of cultured cells
| Freshly isolated cells | 4-day-cultured cells (Type I) | 8-day-cultured cells (Type II) | 12-day-cultured cells (Type III) | |
|---|---|---|---|---|
| Cm (pF) | 157 ± 8 (8) | 153 ± 5 (7) | 263 ± 12 *† (4) | 313 ± 12 *†‡ (7) |
| Ta (mV) | -108·0 ± 1·5 (10) | -92·0 ± 2·5 * (7) | -75·0 ± 2·0 *† (4) | -63·0 ± 1·0 *†‡ (7) |
| Vrev (mV) | -29·0 ± 0·1 (7) | -31·2 ± 0·1 (6) | -27·6 ± 0·1 (6) | -23·0 ± 0·1 (10) |
| gfmaxV (pS pF−1) | 13·90 ± 0·40 (10) | 15·45 ± 0·77 (6) | 33·02 ± 0·51 *† (4) | 39·15 ± 0·44 *†‡ (7) |
| gfmax (pS pF−1) | 15·00 ± 0·15 (7) | 16·58 ± 0·18 (6) | 33·57 ± 0·21 *† (6) | 47·36 ± 0·15 *†‡ (10) |
| V0·5 (mV) | -138·8 ± 0·9 (10) | -127·7 ± 2·0 * (7) | -108·1 ± 0·9 *† (4) | -96·9 ± 0·7 *†‡ (7) |
| S | 10·31 ± 0·80 | 12·60 ± 1·50 | 12·47 ± 0·71 | 11·66 ± 0·60 |
Cm, cell membrane capacitance; Ta, potential for activation threshold; Vrev, reversal potential; gfmaxV, maximum conductance obtained from Boltzmann fitting (Fig. 2); gfmax, slope of the fully activated current (Fig. 3); V0·5, half-maximum voltage; and S, slope factor. Values are means ± S.E.M.
*
P < 0·01 compared with freshly isolated cells
†
P < 0·01 compared with type I cells
‡
P < 0·01 compared with type II cells.