Table I.
Caffeine-induced Ca2+ Release in CHO Cells Expressing RyR-wt and RyR-C*
| Initial [Ca2+]i | [Ca2+]i after caffeine‡ | [Ca2+]i before Thg§ | [Ca2+]i after Thg§ | |||||
|---|---|---|---|---|---|---|---|---|
| nM | ||||||||
| Control | 170.2 | 170.2 | 170.2 | 285.1 | ||||
| 210.0 | 210.0 | 210.0 | 933.3 | |||||
| 191.2 | 191.2 | 191.2 | 665.6 | |||||
| 256.0 | 256.0 | 256.0 | 665.6 | |||||
| 200.2 | 200.2 | 200.2 | 1176 | |||||
| 227.9 | 227.9 | 227.9 | 512.0 | |||||
| Average ± SEM | 209.3 ± 12.2 | 209.3 ± 12.2 | 209.3 ± 12.2 | 706.3 ± 127.9 | ||||
| RyR-wt | 135.8 | 1808 | 487.2 | 693.7 | ||||
| 292.9 | 1456 | 386.9 | 476.0 | |||||
| 207.2 | 638.4 | 465.9 | 560.0 | |||||
| 131.5 | 987.0 | ND | ND | |||||
| Average ± SEM | 191.9 ± 37.9 | 1222.4 ± 257.2 | 446.7 ± 30.5 | 576.6 ± 63.4 | ||||
| RyR-C | 207.7 | 207.7 | 171.7 | 355.1 | ||||
| 476.0 | 476.0 | 206.7 | 5376 | |||||
| 310.9 | 310.9 | 336.0 | 1209 | |||||
| 600.3 | 600.3 | 600.3 | 806.4 | |||||
| 512.8 | 512.8 | 512.8 | 776.0 |
*
Each experiment was done with ∼106 cells.
‡
10 mM caffeine was applied to the cell suspension under continuous stirring.
§
500 nM thapsigargin was applied to the cell suspension under continuous stirring.